Fixup gtid formating

Signed-off-by: Arthur Gautier <baloo@gandi.net>

Author: Arthur Gautier

pymysqlreplication/event.py

@@ -65,8 +65,8 @@ def gtid(self):
         Eg: 3E11FA47-71CA-11E1-9E33-C80AA9429562:23
         See: http://dev.mysql.com/doc/refman/5.6/en/replication-gtids-concepts.html"""
         nibbles = binascii.hexlify(self.sid).decode('ascii')
-        gtid = '%s-%s-%s-%s:%d' % (
-            nibbles[:8], nibbles[8:12], nibbles[12:16], nibbles[16:], self.gno
+        gtid = '%s-%s-%s-%s-%s:%d' % (
+            nibbles[:8], nibbles[8:12], nibbles[12:16], nibbles[16:20], nibbles[20:], self.gno
         )
         return gtid