ci: allow the temporary repo to use the master branch

.github/workflows/host_docs.yaml

@@ -44,6 +44,7 @@ jobs:
           git init
           touch .nojekyll
           git add -A
+          git config --system init.defaultBranch master
           git config --local user.email "[email protected]"
           git config --local user.name "GitHub Action"
           git config --system --add safe.directory /github/workspace/docs/build/html