ci: fix PR checks (install pyyaml before parsing)

.gitea/workflows/pr.yaml

@@ -4,24 +4,23 @@ on:
   pull_request:
 
 jobs:
-  # validate the consumer-facing workflows答复 lint (YAML/structure)
+  # Validate the workflow yaml files parse (PyYAML via pip only when needed)
-  hadolint-shim:
+  yaml-parse:
     runs-on: ubuntu-latest
     steps:
-      - name: Lint the workflow yaml files
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+      - name: Parse all workflow yaml files
         run: |
-          # Just ensure the yaml files parse and each uses supported fields
+          pip install pyyaml --quiet
           python3 - <<'EOF'
-          import sys, yaml, glob
+          import glob, yaml
-          bad = 0
           for f in glob.glob('.gitea/workflows/*.yaml'):
               with open(f) as fh:
                   yaml.safe_load(fh.read())
               print(f, 'ok')
-          sys.exit(1 if bad else 0)
           EOF
 
-  # Validate the CENTRAL config.json itself with renovate-config-validator
+  # Validate the central config.json itself with renovate-config-validator
   validate-central-config:
     uses: ./.gitea/workflows/validate.yaml
     with: