Simplify docker build, use stable PHP 8 image

.github/workflows/ci.yml

@@ -15,18 +15,13 @@ jobs:
 
     strategy:
       matrix:
-        php_version: ["7.4"]
-        php_target: ["php:7.4-cli"]
+        php: ["7.4", "8.0"]
         laravel: ["^6.0", "^8.0"]
-        include:
-          - php_version: "8.0"
-            php_target: "php:8.0.0RC5-cli"
-            laravel: "^8.0"
 
     steps:
     - uses: actions/checkout@v2
     - name: Start docker containers
-      run: PHP_TARGET=${{ matrix.php_target }} PHP_VERSION=${{ matrix.php_version }} docker-compose up -d
+      run: PHP_VERSION=${{ matrix.php }} docker-compose up -d
     - name: Install dependencies
       run: docker-compose exec -T test composer require --no-interaction "laravel/framework:${{ matrix.laravel }}"
     - name: Run tests

docker-compose.yml

@@ -5,7 +5,6 @@ services:
             context: .
             args:
               PHP_VERSION: ${PHP_VERSION}
-              PHP_TARGET: ${PHP_TARGET}
         depends_on:
             mysql:
                 condition: service_healthy