fix warnings

Author: pragatimodi

firebase_admin/multi_factor_config_mgt.py

@@ -85,7 +85,7 @@ def __init__(self, data):
                 if not isinstance(data, dict):
                     raise ValueError(
                         'Invalid data argument in TOTPProviderServerConfig'
-                        'constructor: {0}'.format(data))
+                        ' constructor: {0}'.format(data))
                 self._data = data
 
             @property