Update PHPUnit (gnikyt#894)

Author: lucasmichot

phpunit.xml.dist

@@ -1,9 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/8.0/phpunit.xsd"
          backupGlobals="false"
          backupStaticAttributes="false"
-         bootstrap="vendor/autoload.php"
          colors="true"
          convertErrorsToExceptions="true"
          convertNoticesToExceptions="true"