Log Message:
Update ruby-mysql2 to 0.4.3.

0.4.3

New Features

* Add method Client#ssl_cipher to expose mysql_get_ssl_cipher
* Add method Result#free to immediately free a result set
* Add connection flag automatic_close: true/false to determine whether to
  work around connections being closed by garbage collection in a child
  after a fork. Default is true, which restores behavior prior to 0.3.16.

Bugfixes

* Fix to hold the GVL between mysql_stmt_execute and mysql_stmt_store_result
  to prevent commands hitting the wire out of sync (e.g. if a GC run occurs
  in the middle)
* Fix BigDecimal arguments to Prepared Statements were ignored
* Fix rake re-definition warning

Changes

* Add Ruby 2.3 to the Travis CI matrix
* Allow nil for timeouts instead of casting to 0 when creating a Client
  instance
* Add connection flag automatic_close: true/false to determine whether to
  work around connections being closed by garbage collection in a child
  after a fork. Default is true, which restores behavior prior to 0.3.16.