Make Lint/RedundantRequireStatement mark set as a redundant require in Ruby 3.2+

[Drenmi]

In Ruby 3.2, set will be included by default.

From the Ruby announcement:

Set is now available as a builtin class without the need for require "set". [Feature #16989] It is currently autoloaded via the Set constant or a call to Enumerable#to_set.

This PR updates Lint/RedundantRequireStatement to flag require "set" when configured to inspect Ruby 3.2 or higher.

---

Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.

[bbatsov]

Finally! 🚀