Add the ability to backport to main (#5992)

* Update .mergify.yml

* Update .mergify.yml

Co-authored-by: Joe Peeples <[email protected]>

---------

Co-authored-by: Joe Peeples <[email protected]>
Co-authored-by: Janeen Mikell Roberts <[email protected]>

Author: 3 people

.mergify.yml

@@ -13,6 +13,19 @@ pull_request_rules:
             git merge upstream/{{base}}
             git push upstream {{head}}
             ```
+  - name: backport patches to main branch
+    conditions:
+      - merged
+      - label=backport-main
+    actions:
+      backport:
+        assignees:
+          - "{{ author }}"
+        labels:
+          - "backport"
+        branches:
+          - "main"
+        title: "[{{ destination_branch }}] {{ title }} (backport #{{ number }})"
   - name: backport patches to 8.17 branch
     conditions:
       - merged