Only release on tag

Author: saulshanabrook

.github/workflows/publish.yml

@@ -22,6 +22,7 @@ jobs:
     - run: yarn build
     - run: yarn pack -f package.tgz
     - uses: softprops/action-gh-release@v2
+      if: startsWith(github.ref, 'refs/tags/')
       with:
         files: package.tgz
   lint: