Use PHP 8.5 in all dev and CI tool configurations

[joeparsons]

Motivation

• We currently use PHP 8.4 for all of our local dev and CI configs
• Drupal 11.3 adds support for PHP 8.5
• 8.3 is the minimum PHP version for Drupal 11.x
• 8.5 will be the minimum PHP version for Drupal 12.x

The sooner we can start testing PHP 8.5 compatibility, the better.

Also worth noting:

• We currently use 8.3 as the default PHP version for the Pantheon upstream
• PHP 8.4 is available on Pantheon
• PHP 8.5 is not yet available on Pantheon

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Proposed Resolution

Change the default PHP version for local dev and CI configs to PHP 8.5 in the main branch of the az_quickstart repo after we've created the 3.3.x release branch / 3.3.0-alpha1 release