Bump test utilities

Author: WyriHaximus

composer.json

@@ -17,7 +17,7 @@
         "thecodingmachine/safe": "^1.3"
     },
     "require-dev": {
-        "wyrihaximus/async-test-utilities": "^3.4.20"
+        "wyrihaximus/async-test-utilities": "^4.0"
     },
     "config": {
         "platform": {