fix: mlog create 不带mtask时报错

apps/wpm/serializers.py

@@ -122,7 +122,8 @@ class MlogSerializer(CustomModelSerializer):
         return super().update(instance, validated_data)
 
     def validate(self, attrs):
-        mtask = attrs['mtask']
+        mtask = attrs.get('mtask', None)
+        if mtask:
             handle_date = attrs['handle_date']
             if handle_date >= mtask.start_date and handle_date <= mtask.end_date:
                 pass