feat: drainserializer mgroup_name

apps/enp/serializers.py

@@ -8,6 +8,7 @@ from django.utils import timezone
 
 class DrainSerializer(CustomModelSerializer):
     """Serializer for Drain model"""
+    mrgoup_name = serializers.CharField(source='mgroup.name', read_only=True)
 
     class Meta:
         model = Drain