Drop Python 3.9 support (#545)

## Summary
Removes support for Python 3.9, which has reached end-of-life, and
updates all configuration and documentation to reflect Python 3.10+ as
the minimum supported version. This simplifies dependency constraints
and aligns with current Python support lifecycle.

## Changes

### Configuration Updates
- Updated `pyproject.toml`:
  - Changed `requires-python` from `">=3.9"` to `">=3.10"`
  - Removed `"Programming Language :: Python :: 3.9"` trove classifier
  - Updated Ruff `target-version` from `"py39"` to `"py310"`
  - Updated Black `target-version` from `["py39"]` to `["py310"]`
- Simplified dependency constraints by removing Python 3.9-specific
conditions:
- `pandas-stubs`: Removed Python 3.8-3.9 fallback, now uses single
version constraint
- `numpy`: Removed Python 3.8-3.9 fallback, now uses single version
constraint
- `pytest-benchmark`: Simplified condition from `python_version>='3.9'
and python_version<'4.0'` to `python_version<'4.0'`
- `sphinx`: Simplified condition from `python_version>='3.9' and
python_version<'3.11'` to `python_version<'3.11'`
- `myst-parser`: Removed Python 3.9-3.10 fallback, now uses single
version constraint
- `grpcio`: Simplified condition from `python_version>='3.8' and
python_version<'3.11'` to `python_version<'3.11'`
- `pandas`: Simplified condition from `python_version>='3.9' and
python_version<'3.13'` to `python_version<'3.13'`

### Documentation Updates
- Updated `README.md`: Changed prerequisites from "Python 3.9 and
greater" to "Python 3.10 and greater", and updated tested versions from
"3.9 to 3.13" to "3.10 to 3.13"
- Updated `docs/index.rst`: Changed prerequisites from "Python 3.9 and
greater" to "Python 3.10 and greater", and updated tested versions from
"3.9 to 3.13" to "3.10 to 3.13"
- Updated `docs/upgrading.md`: Added breaking change note in the 7.x
section documenting the removal of Python 3.9 support

## Breaking Changes
⚠️ **Python 3.9 is no longer supported.** Users must upgrade to Python
3.10 or later to use this version of the SDK.

## Impact
- **Users on Python 3.9**: Must upgrade to Python 3.10+ to continue
using the SDK
- **Dependency resolution**: Simplified constraints may allow newer
package versions to be installed
- **CI/CD**: No changes needed as workflows already use parameterized
Python versions (3.10, 3.11, 3.12, 3.13)

## Rationale
Python 3.9 reached end-of-life on October 2, 2025. Dropping support
allows us to:
- Simplify dependency management by removing version-specific
constraints
- Take advantage of Python 3.10+ features and improvements
- Reduce maintenance burden by focusing on actively supported Python
versions
- Align with the Python community's support lifecycle

## Files Changed
- `pyproject.toml`
- `README.md`
- `docs/index.rst`
- `docs/upgrading.md`

Author: jhamon

README.md

@@ -19,7 +19,7 @@ For notes on changes between major versions, see [Upgrading](./docs/upgrading.md
 
 ## Prerequisites
 
-- The Pinecone Python SDK is compatible with Python 3.9 and greater. It has been tested with CPython versions from 3.9 to 3.13.
+- The Pinecone Python SDK is compatible with Python 3.10 and greater. It has been tested with CPython versions from 3.10 to 3.13.
 - Before you can use the Pinecone SDK, you must sign up for an account and find your API key in the Pinecone console dashboard at [https://app.pinecone.io](https://app.pinecone.io).
 
 ## Installation

docs/index.rst

@@ -71,7 +71,7 @@ For notes on changes between major versions, see [Upgrading](./docs/upgrading.md
 Prerequisites
 =============
 
-* The Pinecone Python SDK is compatible with Python 3.9 and greater. It has been tested with CPython versions from 3.9 to 3.13.
+* The Pinecone Python SDK is compatible with Python 3.10 and greater. It has been tested with CPython versions from 3.10 to 3.13.
 * Before you can use the Pinecone SDK, you must sign up for an account and find your API key in the Pinecone console dashboard at `https://app.pinecone.io <https://app.pinecone.io>`_.
 
 Installation

pyproject.toml

@@ -3,7 +3,7 @@ name = "pinecone"
 version = "7.3.0"
 description = "Pinecone client and SDK"
 readme = "README.md"
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 license = { text = "Apache-2.0" }
 authors = [
     { name = "Pinecone Systems, Inc.", email = "[email protected]" }
@@ -17,7 +17,6 @@ classifiers = [
     "Intended Audience :: Science/Research",
     "Intended Audience :: System Administrators",
     "Operating System :: OS Independent",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
@@ -40,7 +39,7 @@ dependencies = [
 
 [project.optional-dependencies]
 grpc = [
-    "grpcio>=1.44.0,<1.59.0; python_version>='3.8' and python_version<'3.11'",
+    "grpcio>=1.44.0,<1.59.0; python_version<'3.11'",
     "grpcio>=1.59.0,<1.68.0; python_version>='3.11' and python_version<'3.13'",
     "grpcio>=1.68.0; python_version>='3.13'",
     "googleapis-common-protos>=1.66.0",
@@ -56,36 +55,33 @@ types = [
     "mypy>=1.6.1,<2.0.0",
     "types-urllib3>=1.26.25.14,<1.27.0.0",
     "grpc-stubs>=1.53.0.3,<1.54.0.0",
-    "pandas-stubs>=2.1.1.230928,<2.2.0.0; python_version>='3.9'",
-    "pandas-stubs>=1.5.3.230321,<1.6.0.0; python_version>='3.8' and python_version<'3.9'",
+    "pandas-stubs>=2.1.1.230928,<2.2.0.0",
     "types-tqdm>=4.66.0.3,<4.67.0.0",
     "types-protobuf>=4.24.0.4,<4.25.0.0",
     "types-python-dateutil>=2.9.0.20241003",
 ]
 dev = [
     "pre-commit>=3.0.0,<4.0.0",
-    "numpy>=1.22; python_version>='3.9'",
-    "numpy>=1.21,<1.22; python_version>='3.8' and python_version<'3.9'",
-    "pandas>=1.3.5,<2.2.3; python_version>='3.9' and python_version<'3.13'",
+    "numpy>=1.22",
+    "pandas>=1.3.5,<2.2.3; python_version<'3.13'",
     "pandas>=2.2.3; python_version>='3.13'",
     "pytest==8.2.0",
     "pytest-asyncio>=0.25.2,<0.26.0",
     "pytest-cov==2.10.1",
     "pytest-mock==3.6.1",
     "pytest-retry>=1.7.0,<2.0.0",
     "pytest-timeout==2.2.0",
-    "pytest-benchmark==5.0.0; python_version>='3.9' and python_version<'4.0'",
+    "pytest-benchmark==5.0.0; python_version<'4.0'",
     "urllib3_mock==0.3.3",
     "responses>=0.8.1",
     "ruff>=0.9.3,<0.10.0",
     "beautifulsoup4>=4.13.3,<5.0.0",
     "vprof>=0.38,<0.39",
     "tuna>=0.5.11,<0.6.0",
     "python-dotenv>=1.1.0,<2.0.0",
-    "sphinx>=7.4.7,<8.0.0; python_version>='3.9' and python_version<'3.11'",
+    "sphinx>=7.4.7,<8.0.0; python_version<'3.11'",
     "sphinx>=8.2.3,<9.0.0; python_version>='3.11'",
-    "myst-parser>=3.0.1,<4.0.0; python_version>='3.9' and python_version<'3.10'",
-    "myst-parser>=4.0.1,<5.0.0; python_version>='3.10'",
+    "myst-parser>=4.0.1,<5.0.0",
 ]
 
 [project.scripts]
@@ -124,7 +120,7 @@ exclude = [
 
 line-length = 100
 indent-width = 4
-target-version = "py39"
+target-version = "py310"
 
 [tool.ruff.lint]
 # Enable Pyflakes (`F`) and a subset of the pycodestyle (`E`)  codes by default.
@@ -161,4 +157,4 @@ docstring-code-line-length = "dynamic"
 
 [tool.black]
 line-length = 100
-target-version = ["py39"]
+target-version = ["py310"]