Use PHP 8.4 for coding-guidelines job

Author: sebastianbergmann

.github/workflows/ci.yaml

@@ -52,7 +52,7 @@ jobs:
       - name: Install PHP
         uses: shivammathur/setup-php@v2
         with:
-          php-version: 8.3
+          php-version: 8.4
           extensions: none, iconv, json, phar, tokenizer
           coverage: none
           tools: none