ci: pre-commit autoupdate

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

Author: pre-commit-ci[bot]

.pre-commit-config.yaml

@@ -14,7 +14,7 @@ repos:
           - id: pyupgrade
             args: ["--py37-plus"]
     - repo: https://github.com/adamchainz/django-upgrade
-      rev: "1.16.0"
+      rev: "1.18.0"
       hooks:
           - id: django-upgrade
             args: [--target-version, "2.2"]