Support for ruby 2.6.5 version

[jaedung]

Hi,

My application is using ruby version 2.6.5.
It was working in github actions before but the version 2.6.5 can't be found now.

In the readme of this repository, it says a ruby-version of 2.6 or 2.6.x are equivalent.
However, I need to install 2.6.5 on actions because all of my application gems are bundled with the version.

Thanks,
Justin

[MSP-Greg]

If you want a specific Ruby version, I might suggest ruby/setup-ruby