Auto-detect PHP version to use

Author: alcaeus

.github/workflows/composer-validate.yml

@@ -12,9 +12,6 @@ on:
       - "master"
       - "feature/*"
 
-env:
-  PHP_VERSION: "8.2"
-
 jobs:
   composer-validate:
     name: "Check validity of composer.json"
@@ -28,8 +25,6 @@ jobs:
 
       - name: "Install PHP"
         uses: "shivammathur/setup-php@v2"
-        with:
-          php-version: "${{ env.PHP_VERSION }}"
 
       - name: "Run composer validate"
         run: "composer validate --strict"