ci(mergify): upgrade configuration to current format (#596)

Co-authored-by: Mergify <37929162+mergify[bot]@users.noreply.github.com>

Author: mergify[bot]

.github/mergify.yml

@@ -2,13 +2,13 @@ queue_rules:
   - name: default
     # Mergify always respects the branch protection settings
     # so we can left empty mergify own ones
-    conditions: []
+    queue_conditions:
+      - label=merge me
+    merge_conditions: []
+    merge_method: squash
 
 pull_request_rules:
   - name: Automatically merge pull requests
-    conditions:
-      - label=merge me
+    conditions: []
     actions:
       queue:
-        method: squash
-        name: default