use clear instead of {}

[rspadim]

at:

https://github.com/noplay/python-mysql-replication/blob/511b42c8ac2c1682a6e2fd4d6691658245b57987/pymysqlreplication/binlogstream.py#L469

we should use .clear() instead of ={}

https://stackoverflow.com/questions/369898/difference-between-dict-clear-and-assigning-in-python