def compute_changes
      spec_sets_diff!

      old_spec_set.each do |old_gem|
        updated_gem = new_spec_set.find { |new_gem| new_gem.name == old_gem.name }
        next unless updated_gem && old_gem.version != updated_gem.version

        fill_changes(old_gem, updated_gem)
      end
    end
def compute_changes
      spec_sets_diff!

      old_spec_set.each do |old_gem|
        updated_gem = new_spec_set.find { |new_gem| new_gem.name == old_gem.name }
        next unless updated_gem && old_gem.version != updated_gem.version

        fill_changes(old_gem, updated_gem)
      end
    end
Compute the diffs between two `Gemfile.lock`.

 @return [Hash] gems for which there are differences.