chore: update Mergify queue rules

Author: kellertk

.mergify.yml

@@ -1,8 +1,18 @@
 queue_rules:
   - name: default
     conditions:
-      # Conditions to get out of the queue (= merged)
-      - check-success=Run unit tests
+      # Conditions to merge a queued PR
+      - check-success=Run unit tests (windows-latest, 14)
+      - check-success=Run unit tests (windows-latest, 16)
+      - check-success=Run unit tests (windows-latest, 18)
+      - check-success=Run unit tests (ubuntu-latest, 14)
+      - check-success=Run unit tests (ubuntu-latest, 16)
+      - check-success=Run unit tests (ubuntu-latest, 18)
+      - check-success=Run unit tests (macos-latest, 14)
+      - check-success=Run unit tests (macos-latest, 16)
+      - check-success=Run unit tests (macos-latest, 18)
+      - "#approved-reviews-by>=1"
+      - -approved-reviews-by~=author
 
 pull_request_rules:
   - name: Automatically merge on CI success and review approval