Update dependency wyrihaximus/async-test-utilities to v8

Author: renovate[bot]

composer.json

@@ -22,7 +22,7 @@
         "wyrihaximus/react-event-loop-rx-scheduler-hook-up": "^0.1.1"
     },
     "require-dev": {
-        "wyrihaximus/async-test-utilities": "^7.2 || ^5"
+        "wyrihaximus/async-test-utilities": "^7.2 || ^5 || ^8"
     },
     "autoload": {
         "psr-4": {