feat: add backport bot

(cherry picked from commit bb2cae5)

.backport/config.json

@@ -0,0 +1,3 @@
+{
+    "autoMerge": true
+}

.github/workflows/backport.yml

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+name: Automatic backport action
+
+on:
+  pull_request_target:
+    types: ["closed"]
+
+jobs:
+  backport:
+    name: Backport PR
+    runs-on: ubuntu-latest
+    steps:
+      - name: Backport Action
+        uses: sqren/[email protected]
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          auto_backport_label_prefix: backport-to-
+
+      - name: Info log
+        if: ${{ success() }}
+        run: cat ~/.backport/backport.info.log
+
+      - name: Debug log
+        if: ${{ failure() }}
+        run: cat ~/.backport/backport.debug.log