mergify: fix deprecated syntax

Author: mr-c

.mergify.yml

@@ -1,13 +1,16 @@
+queue_rules:
+  - name: default
+
 pull_request_rules:
   - name: Automatic merge on approval and when when GitHub branch protection passes on main
     conditions:
       - "#approved-reviews-by>=1"
       - -draft
       - base=main
     actions:
-      merge:
+      queue:
         method: merge
-        strict: smart+fasttrack
+        name: default
 
 pull_request_rules:
   - name: Automatic merge for leadership team members when there are no reviewers and the label is "ready"
@@ -19,6 +22,6 @@ pull_request_rules:
       - author=@leadership
       - label=ready
     actions:
-      merge:
+      queue:
         method: merge
-        strict: smart+fasttrack
+        name: default