Allow Symfony ^8.0

Author: nicolas-grekas

composer.json

@@ -28,8 +28,8 @@
         "symfony/deprecation-contracts": "^2.5|^3"
     },
     "require-dev": {
-        "symfony/filesystem": "^6.4|^7.0",
-        "symfony/var-exporter": "^6.4|^7.0"
+        "symfony/filesystem": "^6.4|^7.0|^8.0",
+        "symfony/var-exporter": "^6.4|^7.0|^8.0"
     },
     "conflict": {
         "symfony/string": "<7.1"