Merge pull request #100042 from Calinou/ci-xmllint-quiet

GitHub Actions: Use quiet xmllint output to only print error lines

.github/workflows/static_checks.yml

@@ -56,7 +56,7 @@ jobs:
 
       - name: Class reference schema checks
         run: |
-          xmllint --noout --schema doc/class.xsd doc/classes/*.xml modules/*/doc_classes/*.xml platform/*/doc_classes/*.xml
+          xmllint --quiet --noout --schema doc/class.xsd doc/classes/*.xml modules/*/doc_classes/*.xml platform/*/doc_classes/*.xml
 
       - name: Run C compiler on `gdextension_interface.h`
         run: |