style: ruff format 全仓库

行宽 180 下把历史遗留的折行表达式合并，无语义改动。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

conf/serializers.py

@@ -44,7 +44,7 @@ class JudgeServerHeartbeatSerializer(serializers.Serializer):
     cpu_core = serializers.IntegerField(min_value=1)
     memory = serializers.FloatField(min_value=0, max_value=100)
     cpu = serializers.FloatField(min_value=0, max_value=100)
-    action = serializers.ChoiceField(choices=("heartbeat", ))
+    action = serializers.ChoiceField(choices=("heartbeat",))
     service_url = serializers.CharField(max_length=256)