Log Message:
py-pymysql: updated to 0.9.3

0.9.3
* cryptography dependency is optional now.
* Fix old_password (used before MySQL 4.1) support.
* Deprecate old_password.
* Stop sending ``sys.argv[0]`` for connection attribute "program_name".
* Close connection when unknown error is happened.
* Deprecate context manager API of Connection object.