Require PHPUnit 9.3 on PHP 8

Author: GrahamCampbell

bin/simple-phpunit.php

@@ -93,7 +93,10 @@
     }
 };
 
-if (PHP_VERSION_ID >= 70200) {
+if (PHP_VERSION_ID >= 80000) {
+    // PHP 8 requires PHPUnit 9.3+
+    $PHPUNIT_VERSION = $getEnvVar('SYMFONY_PHPUNIT_VERSION', '9.3');
+} elseif (PHP_VERSION_ID >= 70200) {
     // PHPUnit 8 requires PHP 7.2+
     $PHPUNIT_VERSION = $getEnvVar('SYMFONY_PHPUNIT_VERSION', '8.3');
 } elseif (PHP_VERSION_ID >= 70100) {