Thanks Koko, it says…

~$ brew doctor
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: You are using macOS 13.
We do not provide support for this pre-release version.
You will encounter build failures with some formulae.
Please create pull requests instead of asking for help on Homebrew's GitHub,
Twitter or any other official channels. You are responsible for resolving
any issues you experience while you are running this
pre-release version.


Warning: Your Xcode does not support macOS 13.
It is either outdated or was modified.
Please update your Xcode or delete it if no updates are available.
Xcode can be updated from:
  https://developer.apple.com/download/all/


Warning: Ruby version 2.6.10 is unsupported on macOS 13. Homebrew
is developed and tested on Ruby 2.6.9, and may not work correctly
on other Rubies. Patches are accepted as long as they don't cause breakage
on supported Rubies.

I updated Xcode so not sure why it’s saying it is out of date

I upgraded and so far everything is OK.

freaked wee bit when git acting weird (xcrun: error: invalid active developer path) after the update.