Fix more setUp signatures

Author: andrewmy

Tests/Functional/MongodbConsumerTest.php

@@ -19,7 +19,7 @@ class MongodbConsumerTest extends TestCase
      */
     private $context;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->context = $this->buildMongodbContext();
     }

Tests/Spec/MongodbSendAndReceivePriorityMessagesFromQueueTest.php

@@ -18,7 +18,7 @@ class MongodbSendAndReceivePriorityMessagesFromQueueTest extends SendAndReceiveP
 
     private $publishedAt;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();