Log Message:
py-pymysql: updated to 0.8.0

0.8:
* **BACKWARD INCOMPATIBLE** binary_prefix option is added and off
  by default because of compatibility with mysqlclient.
  When you need PyMySQL 0.7 behavior, you have to pass binary_prefix=True.
* **BACKWARD INCOMPATIBLE** MULTI_STATEMENTS client flag is no longer
  set by default, while it was on PyMySQL 0.7.  You need to pass
  client_flag=CLIENT.MULTI_STATEMENTS when you connect to explicitly
  enable multi-statement mode.
* Fixed AuthSwitch packet handling.
* Raise OperationalError for MariaDB's constraint error.
* executemany() accepts query without space between VALUES and (.
* Support config file containing option without value.
* Fixed Connection.ping() returned unintended value.