ci(workflows): add auto-merge workflow (#71)

Author: caugner

.github/workflows/auto-merge.yml

@@ -0,0 +1,17 @@
+name: auto-merge
+
+on:
+  pull_request_target:
+
+# No GITHUB_TOKEN permissions, as we use AUTOMERGE_TOKEN instead.
+permissions: {}
+
+jobs:
+  auto-merge:
+    uses: mdn/workflows/.github/workflows/auto-merge.yml@main
+    if: github.repository_owner == 'mdn'
+    with:
+      target-repo: ${{ github.repository }}
+      auto-merge: true
+    secrets:
+      GH_TOKEN: ${{ secrets.AUTOMERGE_TOKEN }}