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

@@ -5,6 +5,6 @@ pytest-timeout == 2.3.*
 pytest-xdist == 3.5.*
 black == 24.3.*
 moto[cloudformation,s3] == 4.2.*
-mypy == 1.8.*
+mypy == 1.9.*
 ruff == 0.3.*
 twine == 5.0.*