ci: PR checks in the renovate image (pyyaml + config validator)

.gitea/workflows/pr.yaml

@@ -4,14 +4,15 @@ on:
   pull_request:
 
 jobs:
-  # Validate the workflow yaml files parse (PyYAML via pip only when needed)
-  yaml-parse:
+  # All workflow yaml parse + renovate-config-validator on central config
+  validate:
     runs-on: ubuntu-latest
+    container: renovate/renovate:43
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
       - name: Parse all workflow yaml files
+        # the renovate image ships its own python + pyyaml
         run: |
-          pip install pyyaml --quiet
           python3 - <<'EOF'
           import glob, yaml
           for f in glob.glob('.gitea/workflows/*.yaml'):
@@ -19,9 +20,5 @@ jobs:
                   yaml.safe_load(fh.read())
               print(f, 'ok')
           EOF
-
-  # Validate the central config.json itself with renovate-config-validator
-  validate-central-config:
-    uses: ./.gitea/workflows/validate.yaml
-    with:
-      config_path: config.json
+      - name: Validate central Renovate config
+        run: renovate-config-validator config.json