fix: stabilize pages deploy and add missing-paper issue template

Author: Nora

.github/workflows/deploy.yml

@@ -63,9 +63,11 @@ jobs:
         run: mkdocs build
 
       - name: Setup Pages
+        if: github.event_name == 'push'
         uses: actions/configure-pages@v4
 
       - name: Upload artifact
+        if: github.event_name == 'push'
         uses: actions/upload-pages-artifact@v3
         with:
           path: ./site
@@ -76,7 +78,7 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     runs-on: ubuntu-latest
     needs: build
-    if: github.ref == 'refs/heads/main' || github.ref == 'refs/heads/master'
+    if: github.event_name == 'push' && (github.ref == 'refs/heads/main' || github.ref == 'refs/heads/master')
     steps:
       - name: Deploy to GitHub Pages
         id: deployment