don't deploy gh-pages

.github/workflows/docs.yml

@@ -17,6 +17,8 @@ concurrency:
 jobs:
     build:
         name: GitHub Pages
+        # Only respect triggers from our develop branch, ignore that of forks
+        if: github.repository == 'vector-im/element-web'
         runs-on: ubuntu-latest
         steps:
             - name: Fetch element-desktop