make docs deploy to gh pages correctly skip the step unless pushing a tag

Author: aerispaha

.github/workflows/documentation.yml

@@ -48,7 +48,7 @@ jobs:
           path: './docs/build'
 
   deploy:
-    if: startsWith(github.event.ref, 'refs/tags/v')
+    if: startsWith(github.ref, 'refs/tags/v')
     environment:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}