Dropped support for TargetRubyVersion: "2.1"

[bazay]

In the latest release, v0.60.0, it appears Rubocop has dropped support for TargetRubyVersion being less than 2.2.

This gem is listed as a runtime dependency in rubocop:
https://github.com/rubocop-hq/rubocop/blob/master/rubocop.gemspec#L41

Yet since this project is requiring an older, unsupported ruby version i.e. 2.1:
https://github.com/sickill/rainbow/blob/master/.rubocop.yml#L6

It is preventing my project to build properly in CircleCI whilst using a ruby 2.4.1, throwing the following error:

Error: Unsupported Ruby version 2.1 found in `TargetRubyVersion` parameter (in vendor/bundle/ruby/2.4.0/gems/rainbow-3.0.0/.rubocop.yml). 2.1-compatible analysis was dropped after version 0.58.
Supported versions: 2.2, 2.3, 2.4, 2.5, 2.6

[bazay]

Looked into this further, and it appears to have been caused by using Exclude merge strategy in my project's .rubocop.yml file.

inherit_mode:
  merge:
    - Exclude

Seeing as this issue doesn't appear to be related to the gem I'm going to self-close this ticket.

However, you still might want to update the TargetRubyVersion :)