Update the Dependabot auto-merge workflow to select the repository's allowed merge method and simplify PR filtering.
Changes:
- Renamed the workflow step to "Auto-merge Dependabot dependency PRs".
- Removed version parsing and update-type checks; no longer requires parsing PR title for major/minor/patch.
- Fetch repository settings and choose merge method from `allow_merge_commit`, `allow_squash_merge`, or `allow_rebase_merge`; fail if none allowed.
- Broaden Dependabot detection to any author string containing "dependabot" and require the `dependencies` label before attempting auto-merge.
- Preserve `automerge:disabled` label to skip merges when present.
- Use the chosen `merge_method` (instead of hardcoded `squash`) and log which method was used.
Rationale: support repositories with different merge configurations and simplify auto-merge rules by relying on labels rather than title version parsing.
xixu-me
dependabot[bot]