test: lowest needs var-exporter > 6.1.1

Author: soyuka

composer.json

@@ -95,6 +95,7 @@
         "doctrine/mongodb-odm": "<2.2",
         "doctrine/persistence": "<1.3",
         "symfony/service-contracts": "<3",
+        "symfony/var-exporter" : "<6.1.1", 
         "phpunit/phpunit": "<9.5",
         "phpspec/prophecy": "<1.15",
         "elasticsearch/elasticsearch": ">=8.0"