How to change Xcode/CLT version in CI/Github Actions

[Joshua Root]

On 22/11/2023 01:46, Dave Allured - NOAA Affiliate wrote:
> 
> There is no possible port workaround for an Xcode/CLT mismatch such as 
> the current situation on CI OS 13 which I mentioned earlier.  CI OS 13 
> is in an illegal condition, according to Macports specifications.
Is it? We certainly recommend having the same version of both installed, 
but generally ports should be building with one or the other depending 
on the use_xcode setting.

- Josh