add debug flag

Author: krichprollsch

.github/workflows/build.yml

@@ -34,3 +34,5 @@ jobs:
           # For pull requests, export results to the build cache.
           # Otherwise, push to a registry.
           outputs: ${{ github.event_name == 'pull_request' && 'type=cacheonly' || 'type=registry' }}
+          # add debug flag
+          build-args: DEBUG=true