Use Ruby 3.3.0-rc1 to fix mysql_ar_rspec

[HeyNonster]

In Ruby < 3.3.0 the default timeout gem version is 0.3.1. ActiveRecord >= 7.1 requires timeout >= 0.4.0. This causes a problem with inline gemfiles because rubygems loads timeout 0.3.1 then ActiveRecord tries to require timeout 0.4.1, but timeout is already loaded and we end up with this error:

runtime.rb:304:in `check_for_activated_spec!': You have already activated timeout 0.3.1, but your 
Gemfile requires timeout 0.4.1. Since timeout is a default gem, you can either remove your 
dependency on it or try updating to a newer version of bundler that supports timeout as a default 
gem. (Gem::LoadError)

Ruby 3.3.0 bumps the default timeout version to 0.4.0 though, so we can use Ruby 3.3.0 to fix ci.

Locally, we need to wait for a new rubygems version that installs timeout to >= 0.4.0 by default or run gem install --default timeout -v 0.4.1.