ci: Set spe-tags=, (#1009)

Signed-off-by: Andreas Heinrich <andreas.heinrich@rwth-aachen.de>

Author: andistorm

.github/workflows/build_and_test.yaml

@@ -51,6 +51,7 @@ jobs:
         uses: docker/metadata-action@v5
         with:
           images: ${{ env.BUILD_KIT_IMAGE_NAME }}
+          sep-tags: ","
       - name: Set output tag
         id: buildkit_tag
         shell: python3 {0}