⬆ Bump mypy from 1.8.0 to 1.9.0 (#271)

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
...

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

pyproject.toml

@@ -94,7 +94,7 @@ test = [
     "pytest>=7.1.3,<9.0.0",
     "pytest-cov>=4.1.0,<5.0.0",
     "pytest-asyncio>=0.20.0",
-    "mypy==1.8.0",
+    "mypy==1.9.0",
     "flake8>=5.0.4",
     "aiofiles>=0.8.0,<24",
     "a2wsgi>=1.9.0,<2",