Add support for Symfony 6.0

Author: mbabker

.github/workflows/ci.yml

@@ -22,6 +22,8 @@ jobs:
                     - php: '7.1'
                       symfony: '4.4.*'
                       dependency: 'lowest'
+                    - php: '8.0'
+                      symfony: '6.0.*'
                 exclude:
                     - php: '7.1'
                       symfony: '5.3.*'
@@ -37,6 +39,12 @@ 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

@@ -14,7 +14,7 @@
     ],
     "require": {
         "php": "^7.1 || ^8.0",
-        "symfony/config": "^4.4 || ^5.3"
+        "symfony/config": "^4.4 || ^5.3 || ^6.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^7.0 || ^8.0 || ^9.0"