Use of old unicode-display_width with new rubocop

[soumyaray]

Dependence on older version of unicode-display_width is causing a conflict with newer rubocop

Because rubocop >= 1.8.0, < 1.43.0 depends on unicode-display_width >= 1.4.0, < 3.0
  and rubocop >= 0.81.0, < 1.8.0 depends on unicode-display_width >= 1.4.0, < 2.0,
  rubocop >= 0.81.0, < 1.43.0 requires unicode-display_width >= 1.4.0, < 3.0.
And because rubocop >= 1.43.0 depends on unicode-display_width >= 2.4.0, < 3.0
  and every version of hirb-unicode depends on unicode-display_width ~> 0.1.1,
  rubocop >= 0.81.0 is incompatible with hirb-unicode >= 0.
So, because Gemfile depends on hirb-unicode >= 0
  and Gemfile depends on rubocop ~> 1.0,
  version solving has failed.

To make everything play well, we have to drop to a very old version of rubocop that doesn't catch any new warnings of the new rubies.