underscore in the build artifact tag name

.github/workflows/sage-test.yml

@@ -140,5 +140,5 @@ jobs:
         run: |
           cd ~/pantheon-local-copies/wpcm-sage-install-tests
           git fetch --tags origin
-          git tag -d pantheon_build_artifacts-$multidev_name
+          git tag -d pantheon_build_artifacts_$multidev_name
           git push origin --delete pantheon_build_artifacts-$multidev_name