feat: add mergify backport support (#226)

Author: tanmoysrt

.mergify.yml

@@ -0,0 +1,20 @@
+pull_request_rules:
+  - name: backport to develop
+    conditions:
+      - label="backport-develop"
+    actions:
+      backport:
+        branches:
+          - develop
+        assignees:
+          - "{{ author }}"
+
+  - name: backport to v1
+    conditions:
+      - label="backport-v1"
+    actions:
+      backport:
+        branches:
+          - v1
+        assignees:
+          - "{{ author }}"