Publish for Scala 2.13

[godenji]

Available on Maven Central for Scala 2.11 and 2.12, but apparently not 2.13.

[cheeseng]

@godenji I have just staged 3.0.8-1 and 3.1.0.1 which includes build for Scala 2.13, @bvenners shall have the honour to release them.

Cheers.