ci: add merge conflict resolution for component_index.json in autofix workflow

Handle merge conflicts in the Update Component Index job by:
- Automatically resolving component_index.json conflicts using --theirs strategy
- Failing if non-generated files have conflicts (requires manual resolution)
- Completing the merge after resolving generated file conflicts

This prevents the workflow from failing when component_index.json has conflicts
during PR updates, as this file is auto-generated and can be safely regenerated.

.github/workflows/py_autofix.yml

@@ -70,6 +70,7 @@ jobs:
         run: |
           git config user.name "github-actions[bot]"
           git config user.email "github-actions[bot]@users.noreply.github.com"
+          git fetch origin ${{ github.base_ref }}
           git merge origin/${{ github.base_ref }} --no-edit || {
             # Check which files have conflicts
             CONFLICTED=$(git diff --name-only --diff-filter=U)