ci(mergify): upgrade configuration to current format

Author: mergify[bot]

.mergify.yml

@@ -1,15 +1,15 @@
 queue_rules:
   - name: default
-    conditions:
+    queue_conditions:
       - base=master
       - label=S:automerge
+    merge_conditions:
+      - base=master
+      - label=S:automerge
+    merge_method: squash
 
 pull_request_rules:
   - name: automerge to master with label S:automerge and branch protection passing
-    conditions:
-      - base=master
-      - label=S:automerge
+    conditions: []
     actions:
       queue:
-        method: squash
-        name: default