Bump pyupgrade from 3.20.0 to 3.21.0 (#362)

Bumps [pyupgrade](https://github.com/asottile/pyupgrade) from 3.20.0 to 3.21.0.
- [Commits](asottile/pyupgrade@v3.20.0...v3.21.0)

---
updated-dependencies:
- dependency-name: pyupgrade
  dependency-version: 3.21.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements-dev.txt

@@ -5,7 +5,7 @@ isort==6.1.0
 mypy==1.15.0
 pre-commit==4.3.0
 pygments==2.19.2
-pyupgrade==3.20.0
+pyupgrade==3.21.0
 tox==4.30.3
 types-requests==2.32.4.20250913
 types-setuptools==80.9.0.20250822