Fix isMariaDB function error

Author: cucuridas@gamil.com

pymysqlreplication/tests/base.py

@@ -67,7 +67,7 @@ def isMySQL80AndMore(self):
 
     def isMariaDB(self):
         if self.__is_mariaDB is None:
-            self.__is_mariaDB = "MariaDB" in self.execute("SELECT VERSION()").fetchone()
+            self.__is_mariaDB = "MariaDB" in self.execute("SELECT VERSION()").fetchone()[0]
         return self.__is_mariaDB
 
     @property