fix version constrain

Author: rodber

composer.json

@@ -15,7 +15,7 @@
         "php": "^8.1",
         "chevere/iterator": "^1.0",
         "chevere/message": "^0.1.0",
-        "symfony/var-exporter": "^7.0"
+        "symfony/var-exporter": "^6.1|^7.0"
     },
     "require-dev": {
         "phpstan/phpstan": "^1.9",