err[ci] Only check commits format in PRs

Author: ao-picterra

.github/workflows/lint_test.yml

@@ -52,6 +52,7 @@ jobs:
         python -m pip install -r requirements.txt
         make html
   guidelines:
+    if: ${{ github.event.pull_request }}
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3