add support to PHPUnit 7.5.x

Author: llaville

composer.json

@@ -11,7 +11,7 @@
     "require": {
         "php": "^7.2|^8.0",
         "psr/log": "^1.0|^2.0|^3.0",
-        "phpunit/phpunit": "^8.0|^9.0"
+        "phpunit/phpunit": "^7.5|^8.0|^9.0"
     },
     "require-dev": {
         "monolog/monolog": "^2.0",