.pre-commit-config.yaml: add pre-cmmit-ci validator

Python 3.12 in Fedora 39 Beta seems incompatible with almost everything

.pre-commit-config.yaml

@@ -8,6 +8,10 @@ ci:
   # https://github.com/pre-commit-ci/issues/issues/83
   autoupdate_schedule: quarterly
 
+# Override hook language versions from system defaults
+default_language_version:
+  python: pypy3
+
 repos:
   - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v4.4.0
@@ -28,6 +32,11 @@ repos:
         # File types depending on trailing whitespace. Use identify-cli
         exclude_types: [svg, markdown, tsv]
 
+  - repo: https://github.com/pre-commit-ci/pre-commit-ci-config
+    rev: v1.6.1
+    hooks:
+      - id: check-pre-commit-ci-config
+
   # Markdown Table of Contents generation.
   - repo: https://github.com/thlorenz/doctoc
     rev: v2.2.0