Merge pull request #550 from mcg-web/fix-appveyor-build

Fix Appveyor build

Author: mcg-web

composer.json

@@ -50,7 +50,7 @@
  },
  "require-dev": {
  "doctrine/orm": "^2.5",
- "phpunit/phpunit": "^7.2 || ^8.2",
+ "phpunit/phpunit": "<8.3",
  "react/promise": "^2.5",
  "symfony/asset": "^3.4 || ^4.0",
  "symfony/browser-kit": "^3.4 || ^4.0",