ci: rebase before pushing versioned docs commit

Add `pull: '--rebase --autostash'` to the EndBug/add-and-commit step in
the docs versioning workflow so the release push does not fail when the
default branch has moved forward during the job.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: B4nan

.github/workflows/manual_version_docs.yaml

@@ -126,6 +126,7 @@ jobs:
           add: website/versioned_docs website/versioned_sidebars website/versions.json
           message: "docs: Version docs for v${{ steps.snapshot.outputs.version }} [skip ci]"
           default_author: github_actions
+          pull: '--rebase --autostash'
 
       - name: Resolve output commitish
         id: resolve_commitish