Add current version as a minimum version to gems without version constraints in Gemfile

update_minimum_version.rb

#!/usr/bin/env ruby
file_name = 'Gemfile'
text = File.read(file_name)

new_contents = text.gsub(/^\s*gem ['"]([\w_\-]+)['"]$/) do
  original = Regexp.last_match[0]
  gem_name = Regexp.last_match[1]
  current_version = Gem.loaded_specs[gem_name].version.to_s
  "#{original}, '>= #{current_version}'"
end

File.open(file_name, 'w') do |file|
  file.puts new_contents
end