Upgrade phpunit to 9.4 (#2617)

Author: limingxinleo

composer.json

@@ -24,7 +24,7 @@
         "elasticsearch/elasticsearch": "^7.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^5.7",
+        "phpunit/phpunit": "^9.4",
         "guzzlehttp/ringphp": "~1.0"
     },
     "extra": {