Bump pyupgrade from 3.20.0 to 3.21.0

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:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pyproject.toml

@@ -54,7 +54,7 @@ test = [
 ]
 lint = [
   "ruff==0.14.0",
-  "pyupgrade==3.20.0",
+  "pyupgrade==3.21.0",
   "django-upgrade==1.29.0",
 ]
 docs = [