[TASK] Update php to v8.5

| datasource  | package     | from | to  |
| ----------- | ----------- | ---- | --- |
| github-tags | php/php-src | 8.4  | 8.5 |

Author: renovate[bot]

.github/workflows/tests.yaml

@@ -131,7 +131,7 @@ jobs:
         uses: shivammathur/setup-php@v2
         with:
           # @todo Switch to PHP 8.5 once Box is fully PHP 8.5 compatible
-          php-version: 8.4
+          php-version: 8.5
           ini-file: development
           tools: composer:v2