.ruby-version

* Update to Ruby 2.7

The currently used Ruby 2.5 is pretty old and is nearing its end of
life [1]. This patch updates the used Ruby version to the current
stable version.

[1] https://www.ruby-lang.org/en/downloads/branches/



* Update .ruby-version to 2.7.2

Co-authored-by: Ahmad Farhat <ahmad.af.farhat@gmail.com>