Release/v3.0.0

[jeipollack]

Summary

Update the development workflow, Git branching model, and project environment.
Includes extra guidance for working with Scriv-based changelog and updated environment dependencies.
Note: Validation tests and plots are documented in dedicated issues, not in this PR.

What’s changed

• Added Scriv-based changelog workflow to DEV_WORKFLOW.md, including guidance on fragments, [Unreleased], and branching/scope rules.
• Updated Git branching model to include release/vX.Y.Z branches for preparing releases.
• Clarified branch naming conventions and workflow for feature, bug, hotfix, and release branches.
• Updated environment.yml with new versions
• Minor cleanup and clarifications in DEV_WORKFLOW.md text.
• Update to the pull_request_template.md to include release PR checks

How to test / verify

• Open DEV_WORKFLOW.md and verify that the Git workflow diagram and release instructions are accurate.
• Confirm that environment.yml installs successfully in a fresh environment.
• Review CONTRIBUTING.md to ensure changelog fragment creation instructions are clear and consistent with DEV_WORKFLOW.md.
• Review pull_request_template.md for clarity of Release PR preparation
• Optionally, run scriv create in changelog.d/ to check that fragment creation works locally.

Scope

Indicate the type of PR:

• Feature
• Bug fix
• Hotfix
• Documentation / process change
• Internal / refactor

Optionally, note if this PR is part of a larger milestone or set of related PRs.

Changelog

Did this PR introduce user-visible changes?
If yes, a Scriv changelog fragment must be added and committed.

• Changelog fragment added (if applicable)

Reviewer Checklist

Reviewers should confirm the following before approving and merging:

• The PR targets the develop branch
• The PR is assigned to the developer
• Appropriate labels are applied
• The PR is included in relevant projects and/or milestones
• Description clearly explains what has changed
• Issue references included, if applicable
• Code and documentation adhere to current standards (ruff)
• Documentation updates included, if relevant
• CI tests are passing
• All reviewer comments have been addressed

Next Steps / Notes (if applicable)

None