Update dependency phpunit/phpunit to ^9.6.4

| datasource | package         | from  | to    |
| ---------- | --------------- | ----- | ----- |
| packagist  | phpunit/phpunit | 9.6.3 | 9.6.4 |

Author: renovate[bot]

composer.json

@@ -11,7 +11,7 @@
         "cache/integration-tests": "dev-master",
         "cache/tag-interop": "dev-master",
         "infection/infection": "^0.26.19",
-        "phpunit/phpunit": "^9.6.3"
+        "phpunit/phpunit": "^9.6.4"
     },
     "license": "MIT",
     "authors": [