fix "ResourceWarning: Unclosed MongoClient" from PyMongo 4.9

Author: timgraham

django_mongodb/base.py

@@ -173,6 +173,7 @@ def _rollback(self):
 
     def close(self):
         if self.connected:
+            self.connection.close()
             del self.connection
             del self.database
             self.connected = False