Add support for Symfony 6.0

Author: mbabker

.github/workflows/ci.yaml

@@ -24,6 +24,8 @@ jobs:
           - php: '7.2'
             symfony: '4.4.*'
             dependency: 'lowest'
+          - php: '8.0'
+            symfony: '6.0.*'
       fail-fast: false
     steps:
       - name: Checkout
@@ -36,6 +38,12 @@ jobs:
           extensions: pcov
           tools: flex
 
+      - name: Prefer unstable Composer dependencies for Symfony 6.0
+        if: matrix.symfony == '6.0.*'
+        run: |
+          composer config prefer-stable false
+          composer config minimum-stability dev
+
       - name: Get Composer Cache Directory
         id: composer-cache
         run: echo "::set-output name=dir::$(composer config cache-files-dir)"

composer.json

@@ -15,12 +15,12 @@
     "require": {
         "php": "^7.2 || ^8.0",
         "matthiasnoback/symfony-config-test": "^4.0.1",
-        "symfony/dependency-injection": "^4.4 || ^5.3",
-        "symfony/config": "^4.4 || ^5.3",
-        "symfony/yaml": "^4.4 || ^5.3"
+        "symfony/dependency-injection": "^4.4 || ^5.3 || ^6.0",
+        "symfony/config": "^4.4 || ^5.3 || ^6.0",
+        "symfony/yaml": "^4.4 || ^5.3 || ^6.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.0"
+        "phpunit/phpunit": "^8.0 || ^9.0"
     },
     "conflict": {
         "phpunit/phpunit": "<8.0"