Fix tarball naming for release-tarball Github Actions workflow.

Prior to this change, a tarball would be named:
- `slate-refs.tags.0.76.0-test1.0.tgz`

Now, it will be named:
- `slate-0.76.0-test1.0.tgz`

.github/workflows/release-tarball.yml

@@ -36,5 +36,5 @@ jobs:
         with:
           repo_token: ${{ secrets.GITHUB_TOKEN }}
           file: packages/slate/package.tgz
-          asset_name: slate-${{ github.ref }}.tgz
+          asset_name: slate-${{ github.event.release.tag_name }}.tgz
           tag: ${{ github.ref }}