fix: remove --auto from gh pr merge for immediate Dependabot merge

The --auto flag enables auto-merge which blocks on branch protection
rules (e.g. required reviews). Since the workflow already verifies CI
passed and head SHA matches, merge immediately with --rebase instead.

Author: Pigbibi

.github/workflows/dependabot_auto_merge.yml

@@ -88,4 +88,4 @@ jobs:
         if: steps.merge_guard.outputs.should_merge == 'true'
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        run: gh pr merge "${{ steps.pr.outputs.pr_number }}" --repo "${GITHUB_REPOSITORY}" --rebase --delete-branch --match-head-commit "${{ steps.pr.outputs.head_sha }}" --auto
+        run: gh pr merge "${{ steps.pr.outputs.pr_number }}" --repo "${GITHUB_REPOSITORY}" --rebase --delete-branch --match-head-commit "${{ steps.pr.outputs.head_sha }}"