Remove void return type from test methods

Author: OskarStark

Tests/DependencyInjection/Compiler/AddSecurityVotersPassTest.php

@@ -71,7 +71,7 @@ public function testThatSecurityVotersAreProcessedInPriorityOrder()
         $this->assertCount(4, $refs);
     }
 
-    public function testThatVotersAreTraceableInDebugMode(): void
+    public function testThatVotersAreTraceableInDebugMode()
     {
         $container = new ContainerBuilder();
 
@@ -103,7 +103,7 @@ public function testThatVotersAreTraceableInDebugMode(): void
         $this->assertCount(2, $voters, 'Incorrect count of voters');
     }
 
-    public function testThatVotersAreNotTraceableWithoutDebugMode(): void
+    public function testThatVotersAreNotTraceableWithoutDebugMode()
     {
         $container = new ContainerBuilder();
         $container->setParameter('kernel.debug', false);