ci: use rebase when auto merging dependabot PRs

Keeps the history more readable.

Author: slisson

.github/workflows/dependabot-auto-merge.yaml

@@ -18,7 +18,7 @@ jobs:
 
       - name: Enable auto-merge on the PR
         if: (steps.metadata.outputs.update-type == 'version-update:semver-patch' || steps.metadata.outputs.update-type == 'version-update:semver-minor')
-        run: gh pr merge --auto --merge "$PR_URL"
+        run: gh pr merge --auto --rebase "$PR_URL"
         env:
           PR_URL: ${{github.event.pull_request.html_url}}
           GH_TOKEN: ${{secrets.GITHUB_TOKEN}}