Only publish to test.PyPI on tag pushes

Author: ldionne

.github/workflows/build-and-publish-package.yml

@@ -29,7 +29,8 @@ jobs:
 
   publish-to-testpypi:
     runs-on: ubuntu-latest
-    if: github.event_name == 'push' && github.ref == 'refs/heads/main' # only publish to test.PyPI on pushes to main
+    if: startsWith(github.ref, 'refs/tags/') # only publish to test.PyPI on tag pushes (for the time being)
+    # if: github.event_name == 'push' && github.ref == 'refs/heads/main' # only publish to test.PyPI on pushes to main
 
     name: Publish LNT to TestPyPI
     needs: [build]