Merge pull request #121 from clue-labs/phpunit8-backport

[0.6.x] Update test environment to fix tests on legacy PHP 7.2 with PHPUnit 8.5

Author: WyriHaximus

composer.json

@@ -32,9 +32,9 @@
         "react/stream": "^1.4"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.36",
+        "phpunit/phpunit": "^9.6 || ^8.5 || ^5.7 || ^4.8.36",
         "react/socket": "^1.16",
-        "sebastian/environment": "^5.0 || ^3.0 || ^2.0 || ^1.0"
+        "sebastian/environment": "^5.0 || ^4.0 || ^2.0 || ^1.0"
     },
     "autoload": {
         "psr-4": {