Do not keep history of gh-pages to avoid repository bloat

.github/workflows/doxygen.yml

@@ -22,4 +22,5 @@ jobs:
       uses: peaceiris/actions-gh-pages@v3
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}
-        publish_dir: ./Build/Doxygen
+        publish_dir: ./Build/Doxygen
+        force_orphan: true