Altis v23 - minimum PHP version is 8.1.30

[owaincuvelier]

Steps to reproduce:

1. Run travis build on Altis v23
2. phpenv will fail to install PHP 8.1

PHP should install and continue to run composer scripts. However, phpenv no longer has 8.1 available, the minimum version appears to be 8.1.30, which is what our version should be set to in Altis Dev Tools for Altis v23.

I think we just need to change: https://github.com/humanmade/altis-dev-tools/blob/v23-branch/travis/altis.yml#L8 to 8.1.30

Acceptance criteria:

• ...