Remove phpunit dev dependency.

Author: dereuromark

composer.json

@@ -20,8 +20,7 @@
  },
  "require-dev": {
  "instituteweb/composer-scripts": "^1.1",
- "phauthentic/file-storage-image-processor": "dev-master",
- "phpunit/phpunit": "^9.0"
+ "phauthentic/file-storage-image-processor": "dev-master"
  },
  "suggest": {
  "phauthentic/file-storage-image-processor": "For image processing"