Bump mypy from 1.8.0 to 1.9.0 (#1432)

Bumps [mypy](https://github.com/python/mypy) from 1.8.0 to 1.9.0.
- [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
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements/testing.txt

@@ -9,4 +9,4 @@ ruff==0.3.2
 setuptools==69.1.1
 tox==4.14.1
 tox-gh-actions==3.2.0
-mypy==1.8.0
+mypy==1.9.0