[pre-commit.ci] pre-commit autoupdate

updates:
- [github.com/adamchainz/django-upgrade: 1.19.0 → 1.21.0](adamchainz/django-upgrade@1.19.0...1.21.0)
- [github.com/astral-sh/ruff-pre-commit: v0.5.2 → v0.6.8](astral-sh/ruff-pre-commit@v0.5.2...v0.6.8)

.pre-commit-config.yaml

@@ -1,11 +1,11 @@
 repos:
 - repo: https://github.com/adamchainz/django-upgrade
-  rev: 1.19.0
+  rev: 1.21.0
   hooks:
   - id: django-upgrade
     args: [--target-version, "5.0"]
 - repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.5.2
+  rev: v0.6.8
   hooks:
     # Run the linter.
     - id: ruff