ci(mergify): upgrade configuration to current format

mergify[bot] · web-flow · commit bfd7f905f442 · 2026-06-18T09:26:47.000Z
diff --git a/.mergify.yml b/.mergify.yml
@@ -17,8 +17,5 @@ pull_request_rules:
     actions:
       merge:
         method: merge
-  - name: delete head branch on merged pull requests
-    conditions:
-      - merged
-    actions:
-      delete_head_branch:
+merge_protections_settings:
+  reporting_method: check-runs
