Update CI workflow: pass PHP version as environment variable and use dynamically in Docker image

Added `PHP_VERSION` as an environment variable in the workflow matrix and updated `castor.php` to dynamically use this variable for Docker image references. Default PHP version fallback logic added.

Author: Spomky

.github/workflows/ci.yml

@@ -189,6 +189,7 @@ jobs:
       image: ghcr.io/spomky-labs/phpqa:${{ matrix.php-version }}
     env:
       XDEBUG_MODE: coverage
+      PHP_VERSION: ${{ matrix.php-version }}
     steps:
       - uses: actions/checkout@v4
       - uses: actions/cache@v4

castor.php

@@ -201,11 +201,15 @@ function phpqa(array $command, array $dockerOptions = []): void
         '-e', 'XDEBUG_MODE=off',
     ];
 
+    $phpVersion = getenv('PHP_VERSION')
+        ?: (\PHP_MAJOR_VERSION . '.' . \PHP_MINOR_VERSION)
+            ?: '8.4';
+
     run([
         'docker', 'run',
         ...$defaultDockerOptions,
         ...$dockerOptions,
-        'ghcr.io/spomky-labs/phpqa:8.4',
+        sprintf('ghcr.io/spomky-labs/phpqa:%s', $phpVersion),
         ...$command,
     ]);
 }