return type void is required as of PHPunit 7, breaking test compatibility with PHP < 7.1

tst/Persistence/TrafficLimiterTest.php

@@ -7,14 +7,14 @@ class TrafficLimiterTest extends TestCase
 {
     private $_path;
 
-    public function setUp()
+    public function setUp(): void
     {
         /* Setup Routine */
         $this->_path = sys_get_temp_dir() . DIRECTORY_SEPARATOR . 'trafficlimit';
         TrafficLimiter::setPath($this->_path);
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         /* Tear Down Routine */
         Helper::rmDir($this->_path . DIRECTORY_SEPARATOR);