remove extra parameter (PyMySQL#201)

This produced the error `TypeError: _tuple_literal() missing 1 required positional argument: 'd'` on line 316.

Author: NestorTejero

MySQLdb/connections.py

@@ -297,7 +297,7 @@ def _bytes_literal(self, bs):
             return b'_binary' + x
         return x
 
-    def _tuple_literal(self, t, d):
+    def _tuple_literal(self, t):
         return "(%s)" % (','.join(map(self.literal, t)))
 
     def literal(self, o):