ci: pre-commit autoupdate (#171)

updates:
- [github.com/adamchainz/django-upgrade: 1.16.0 → 1.18.0](adamchainz/django-upgrade@1.16.0...1.18.0)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

.pre-commit-config.yaml

@@ -15,7 +15,7 @@ repos:
         args: ["--py38-plus"]
 
   - repo: https://github.com/adamchainz/django-upgrade
-    rev: '1.16.0'
+    rev: '1.18.0'
     hooks:
       - id: django-upgrade
         args: [--target-version, "3.2"]