Support justinrainbow/json-schema version 6

Author: mvanduijker

composer.json

@@ -25,7 +25,7 @@
 		"php": ">=7.1.0",
 		"ext-json": "*",
 		"symfony/yaml": "^3.4 || ^4 || ^5 || ^6 || ^7",
-		"justinrainbow/json-schema": "^5.2"
+		"justinrainbow/json-schema": "^5.2 || ^6.0"
 	},
 	"require-dev": {
 		"cebe/indent": "*",