Remove Ruby 2.7 support

[HeitorMC]

Removes support for Ruby 2.6 due to EOL.

I also checked that Rails 6.0.x will hit EOL on June 1st, 2023. If you guys want to, I can remove it in this PR, or create a new one :)

[vsppedro]

Thanks for working on this. I think is better to create another PR to remove Rails 6.

[HeitorMC]

Hmmm, the rubocop is failing and I didn't change the file that it's breaking 🤔

Also, that line it's present on the main branch

shoulda-matchers/lib/shoulda/matchers/util/word_wrap.rb

Line 44 in 195153c

LIST_ITEM_REGEXP = /\A((?:[a-z0-9]+(?:\)|\.)|\*) )/.freeze

@vsppedro Do you want me to fix it, or just rerun the pipeline? 😄

[vsppedro]

Hmmm, the rubocop is failing and I didn't change the file that it's breaking thinking

It's because this PR updates the "TargetRubyVersion" in the Rubocop file. We need to update the code according to this new version.

[vsppedro]

I intent to merge this PR first: #1521

It will cause some conflict. If I merge yours first the other contribution would be lost. Sorry.

[HeitorMC]

I intent to merge this PR first: #1521

It will cause some conflict. If I merge yours first the other contribution would be lost. Sorry.

Oh no problem, I was expecting that haha, don't worry!

[vsppedro]

Thank you for working on this!