fixing test and psalm

Author: weaverryan

src/Repository/Repository.php

@@ -22,7 +22,7 @@ class Repository
     /**
      * The webhook secret used by GitHub.
      *
-     * @var string
+     * @var string|null
      */
     private $secret;
 

tests/Subscriber/MilestoneNewPRSubscriberTest.php

@@ -27,7 +27,7 @@ protected function setUp()
     {
         $this->milestonesApi = $this->createMock(MilestonesApi::class);
         $this->subscriber = new MilestoneNewPRSubscriber($this->milestonesApi);
-        $this->repository = new Repository('nyholm', 'symfony', [], null);
+        $this->repository = new Repository('nyholm', 'symfony', null);
 
         $this->dispatcher = new EventDispatcher();
         $this->dispatcher->addSubscriber($this->subscriber);