Use github.ref to get tag version

Author: pflooky

.github/workflows/docs-site-deploy.yaml

@@ -29,4 +29,4 @@ jobs:
             mkdocs-material-
       - run: pip install mkdocs-open-in-new-tab mike
       - run: pip install mkdocs-material
-      - run: mike deploy --push --update-aliases ${{ github.event.release.tag_name }} latest
+      - run: mike deploy --push --update-aliases ${{ github.ref }} latest