Update `gitlab-styles` to v13 to get new Rubocop version

Vitaly Slobodinrequested to merge
vs/update-gitlab-styles-gem into master

Update the gitlab-styles gem to pull new Rubocop version that supports Ruby 3. That includes bumping the gem and regenerating the .rubocop-todo.yml file.

Currently, attempting to run rubocop fails with the following error:

❯ bundle exec rubocop -P
Error: RuboCop found unknown Ruby version 3.2 in `.ruby-version`.
Supported versions: 2.4, 2.5, 2.6, 2.7, 3.0

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