OP-351 - Add phpUnit dependency to fix builds on Sylius 1.12 with PHP 8.0

Author: Szymon Kostrubiec

composer.json

@@ -39,7 +39,7 @@
     "phpstan/phpstan-doctrine": "^1.3",
     "phpstan/phpstan-strict-rules": "^1.3.0",
     "phpstan/phpstan-webmozart-assert": "^1.2.0",
-    "phpunit/phpunit": "^10.5",
+    "phpunit/phpunit": "^9.5 || ^10.5",
     "polishsymfonycommunity/symfony-mocker-container": "^1.0",
     "robertfausk/behat-panther-extension": "^1.1",
     "sylius-labs/coding-standard": "^4.2",