Fix Ruff lint errors line-too-long (E501)

This commit fixes the following lint errors:

```console
pp@DESKTOP-89OPGF3 MINGW64 /c/temp/kaitai_struct/runtime/python (master)
$ ruff --version
ruff 0.14.10

pp@DESKTOP-89OPGF3 MINGW64 /c/temp/kaitai_struct/runtime/python (master)
$ ruff check --statistics $(git ls-files '*.py')
3       E501    line-too-long
Found 3 errors.

pp@DESKTOP-89OPGF3 MINGW64 /c/temp/kaitai_struct/runtime/python (master)
$ ruff check $(git ls-files '*.py')
E501 Line too long (92 > 88)
   --> kaitaistruct.py:489:89
    |
487 |         actual = self._io.read(len(expected))
488 |         if actual != expected:
489 |             msg = f"unexpected fixed contents: got {actual!r}, was waiting for {expected!r}"
    |                                                                                         ^^^^
490 |             # NOTE: this method has always raised `Exception` directly and is now
491 |             # unused and slated for removal, so there's no point in "fixing" it.
    |

E501 Line too long (101 > 88)
   --> kaitaistruct.py:533:89
    |
531 |         num_bytes_left = full_size - pos
532 |         if n > num_bytes_left:
533 |             msg = f"requested to write {n} bytes, but only {num_bytes_left} bytes left in the stream"
    |                                                                                         ^^^^^^^^^^^^^
534 |             raise EndOfStreamError(msg, n, num_bytes_left)
    |

E501 Line too long (109 > 88)
    --> kaitaistruct.py:1105:89
     |
1103 |     def __init__(self):
1104 |         super().__init__(
1105 |             "consistency not checked: _check() has not been called since the last modification of the object"
     |                                                                                         ^^^^^^^^^^^^^^^^^^^^^
1106 |         )
     |

Found 3 errors.
```

Author: generalmimon

kaitaistruct.py

@@ -486,7 +486,10 @@ def ensure_fixed_contents(self, expected):
         )
         actual = self._io.read(len(expected))
         if actual != expected:
-            msg = f"unexpected fixed contents: got {actual!r}, was waiting for {expected!r}"
+            msg = (
+                f"unexpected fixed contents: got {actual!r}, "
+                f"was waiting for {expected!r}"
+            )
             # NOTE: this method has always raised `Exception` directly and is now
             # unused and slated for removal, so there's no point in "fixing" it.
             raise Exception(msg)  # noqa: TRY002
@@ -530,7 +533,10 @@ def _ensure_bytes_left_to_write(self, n, pos):
 
         num_bytes_left = full_size - pos
         if n > num_bytes_left:
-            msg = f"requested to write {n} bytes, but only {num_bytes_left} bytes left in the stream"
+            msg = (
+                f"requested to write {n} bytes, but only "
+                f"{num_bytes_left} bytes left in the stream"
+            )
             raise EndOfStreamError(msg, n, num_bytes_left)
 
     # region Integer numbers
@@ -1102,5 +1108,6 @@ class ConsistencyNotCheckedError(Exception):
 
     def __init__(self):
         super().__init__(
-            "consistency not checked: _check() has not been called since the last modification of the object"
+            "consistency not checked: _check() has not been called "
+            "since the last modification of the object"
         )