Fix commit resolution for Docker builds

.github/workflows/publish.yml

@@ -82,3 +82,4 @@ jobs:
           provenance: false
           # https://docs.github.com/en/packages/working-with-a-github-packages-registry/working-with-the-container-registry#adding-a-description-to-multi-arch-images
           outputs: type=image,name=target,annotation-index.org.opencontainers.image.description=A multi-arch Docker image for the Maybe Rails app
+          build-args: BUILD_COMMIT_SHA=${{ github.sha }}