Added support for phpunit 9

Author: chq81

composer.json

@@ -9,15 +9,15 @@
         }
     ],
     "require": {
-        "php": "^7.2",
+        "php": "^7.2 || ^7.3",
         "flow/jsonpath": "^0.5.0",
         "justinrainbow/json-schema": "^5.0"
     },
     "conflict": {
-        "phpunit/phpunit": "<8.0 || >= 9.0"
+        "phpunit/phpunit": "<8.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.0"
+        "phpunit/phpunit": "^8.0 || ^9.0"
     },
     "autoload": {
         "psr-4": {