Merge pull request #284 from WyriHaximus-labs/3.x-update-test-environment-for-PHP-7.2

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

Author: clue

composer.json

@@ -29,7 +29,7 @@
         "php": ">=7.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.6 || ^7.5"
+        "phpunit/phpunit": "^9.6 || ^8.5 || ^7.5"
     },
     "suggest": {
         "ext-pcntl": "For signal handling support when using the StreamSelectLoop"