chore(deps): update mypy requirement from ~=1.8 to ~=1.9

Updates the requirements on [mypy](https://github.com/python/mypy) to permit the latest version.
- [Changelog](https://github.com/python/mypy/blob/master/CHANGELOG.md)
- [Commits](python/mypy@v1.8.0...1.9.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements-testing.txt

@@ -3,7 +3,7 @@ pytest ~= 8.1
 pytest-cov ~= 4.1
 pytest-xdist ~= 3.5
 twine ~= 5.0
-mypy ~= 1.8
+mypy ~= 1.9
 black ~= 24.3
 ruff ~= 0.3.3
 types-pyyaml ~= 6.0