Fix: Use php:7.4-cli with Composer 2.2.24 for Laravel 7.x

All composer Docker images use PHP 8.x:
- composer:1 = PHP 8.4
- composer:2.0 = PHP 8.0
- composer:2.2 = PHP 8.1

Laravel 7.x requires PHP ^7.2.5, so using php:7.4-cli and installing
Composer 2.2.24 manually provides the correct environment.

.drone.yml

@@ -5,8 +5,9 @@ name: default
 steps:
   # Step 1: Install dependencies and run tests
   - name: test
-    image: composer:1
+    image: php:7.4-cli
     commands:
+      - curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer --version=2.2.24
       - composer install --prefer-dist --no-progress --no-interaction
       - composer validate --strict
       - echo "✓ Composer validation passed"