Backporting ruby 2.7 for gitlab

[Pirate Praveen <praveen@onenetbeyond.org>]

Hi,

gitlab stopped working with ruby 2.5 (they officially dropped support 
long ago, but it was working fine till now). See 
https://gitlab.com/gitlab-org/gitlab/-/issues/225251 for details. In 
last stable release we were lucky things worked with ruby 2.3 even 
though it was not officially supported.

Option 1. Backport ruby 2.7

I could upload it to fasttrack as well, but I'd prefer more people 
benefit it by having it in backports since I'm doing the backport work 
anyway.

On a gitlab installation,
$ ls /usr/share/rubygems-integration/2.5.0/specifications/ -1 |wc -l
47

So we will have to backport at least these many modules as well.

Option 2. Patch gitlab to work with ruby 2.5
We can also try to fix issues with ruby 2.5 as and when we notice it as 
well, but if there not many takers for it, I don't think that can work 
well.

Option 1 requires only packaging knowledge but Option 2 requires ruby 
knowledge.

Thanks
Praveen