⬆️ Bump pyupgrade from 3.15.1 to 3.21.0

Bumps [pyupgrade](https://github.com/asottile/pyupgrade) from 3.15.1 to 3.21.0.
- [Commits](asottile/pyupgrade@v3.15.1...v3.21.0)

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

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

Author: dependabot[bot]