Ruby v3.3.6 missing on Travis CI

[emiliocm9]

Hi, we have a new version of Ruby v3.3.6
It would be good if Travis could support this ruby on both Mac and Linux. Ubuntu 22.04 (x86_64)
https://rubies.travis-ci.org/

[night91]

The ruby 4.0.0 and 4.0.1 are already present, but the ruby 3.3.6, that was released a month before still is not.