only git add php files

.github/workflows/phpcbf.yml

@@ -25,7 +25,7 @@ jobs:
           git config --global user.name "Pantheon Robot"
           DIFF=$(git diff-index --quiet HEAD || echo "true")
           if [ "$DIFF" == "true" ]; then
-            git add .
+            git add *.php
             git commit -m "PHPCBF: Fix coding standards" --no-verify
             git push origin ${{ github.event.pull_request.head.ref }}
             echo "changes_detected=true" >> $GITHUB_ENV