Silence wagtailadmin.W001 in project template test

We don't need to compile the CSS for this

.github/workflows/test.yml

@@ -162,6 +162,7 @@ jobs:
           cd testproject
           tee -a testproject/settings/local.py << EOF
           from warnings import filterwarnings
+          SILENCED_SYSTEM_CHECKS = ["wagtailadmin.W001"]
           # Remove when l18n dependency is updated or removed
           filterwarnings(
               "ignore", "'locale.getdefaultlocale' is deprecated .*"