updated Gemfile due to new ruby versions in docker images

Author: jonasjabari

builder/Gemfile

@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
-ruby '2.6.5'
+ruby '2.7.2'
 
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.2.0'