Merge pull request #188 from WyriHaximus-secret-labs/1.x-update-test-environment-for-PHP-7.2

[1.x] Update test environment for PHP 7.2 to compatible PHPUnit version

Author: clue

composer.json

@@ -31,7 +31,7 @@
         "evenement/evenement": "^3.0 || ^2.0 || ^1.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.36",
+        "phpunit/phpunit": "^9.6 || ^8.5 || ^5.7 || ^4.8.36",
         "clue/stream-filter": "~1.2"
     },
     "autoload": {