ci(mergify): upgrade configuration to current format

.github/mergify.yml

@@ -1,29 +1,16 @@
+
 pull_request_rules:
   # rebase+merge strategy
-  - actions:
+  - name: refactored queue action rule
+    actions:
       queue:
-        name: default
-        # Merge into master with a merge commit
-        method: merge
-        # Update the pr branch with rebase, so the history is clean
-        update_method: rebase
-    name: Put pull requests in the rebase+merge queue
-    conditions:
+queue_rules:
+  - name: default
+    queue_conditions:
       - label=merge me
       - '#approved-reviews-by>=1'
-  # merge+squash strategy
-  - actions:
-      queue:
-        name: default
-        method: squash
-        # both update methods get absorbed by the squash, so we use the most
-        # reliable
-        update_method: merge
-    name: Put pull requests in the squash+merge queue
-    conditions:
       - label=squash+merge me
       - '#approved-reviews-by>=1'
-
-queue_rules:
-  - name: default
     conditions: []
+    merge_method: squash
+    update_method: merge