That problem was specific to Rails 7, 6.1 shouldn’t have that problem and shouldn’t need fixing for that.
I just gave a quick glance at the 6-1-stable branch, and I don’t think there’s really any Ruby 3.1 specific problems.
You might need to do some Gemfile workaround for some stuff that were moved from the stdlib to bundled gems but as far as I know that’s about it.
Anyway, best way to know is to upgrade ruby on a branch and run your CI (if your Ci infra supports it of course)