test: Fix PHPUnit configuration (#320)

Author: theofidry

phpunit.xml.dist

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
-         cacheResultFile="dist/.phpunit.result.cache"
+         cacheDirectory="dist/phpunit-cache"
          bootstrap="vendor/autoload.php"
          beStrictAboutChangesToGlobalState="true"
          beStrictAboutOutputDuringTests="true"