Candidate v0.8.64

@mcaramello Looks good!
I added this change: https://github.com/treasure-data/td-client-ruby/commit/4a792552ac7efd7262cd7a4f18c766d705d65e42 and https://github.com/treasure-data/td-client-ruby/commit/49171e4e23031c693abf8f3dc4a525a7b04b38a7