When I was looking into how to read RubyGem versions in Gemfile’s I was hoping to find some examples to reference but didn’t find quite what I was looking for. I hope these annotated examples are helpful:
gem 'rails', '~> 6.1.4'
gem method says to install Rails at a version greater than or equal to 6.1.4 (>= 6.1.4) and less than 6.2 (< 6.2).
gem 'wisper', '~> 2.0', '>= 2.0.1'
gem method has two arguments. The first says to install the Wisper gem at a version greater than or equal to 2.0 (>= 2.0) and less than 3.0 (< 3.0). The second argument makes it more specific and requires that the version be greater than or equal to 2.0.1.