request: ruby2.3 in jessie-backports

[Grégory Pakosz <gregory@pakosz.fr>]

Hello,

As you may have noticed, Ruby 2.1 reached EOL at the end of March 2016. 
Since then, many Ruby gems dropped support for Ruby 2.1 which makes them 
unusable in Debian stable.

Could you please consider adding ruby2.3 currently in testing to 
jessie-backports as well?

Grégory