Add Rails 7.1 testing

[argvniyx-enroute]

Summary

I stumbled upon an error when trying to add Rails 7.1 support to a journaled dependent: in audit_log.rb, we call skip_audit_log on certain ActiveRecord classes which no longer inherit from ActiveRecord::Base in 7.1, so that would raise with a NoMethodError. This PR:

• Bumps .ruby-version to 3.2.2 (most if not all of us are using >=3.0) as our daily driver, so it's a bit of an ergonomic change)
• Includes rubocop autocorrect changes (the vast majority of these are the frozen_string_literal: true lints; mostly felt the need to do this to unblock running be rake locally)
• Skips calling skip_audit_log on ActiveRecord classes when on Rails 7.1
• Only sets legacy_connection_handling when on Rails 7.0

Other Information

There might be some other things worth considering (not ignoring lockfiles(?), actually using the new connection handling (even if it is only a dummy app)) but I didn't want to drag out a PR that's already pretty big.

Thanks for contributing to Journaled!

/domain @smudge @Betterment/journaled-owners /platform @smudge

[lindan-betterment]

@argvniyx-enroute @smudge: Unblocked! - disabled Semgrep for this repo.