Fix inconsistent status codes

HTTP 401 should be used when logging in (i.e. authenticating) would make
a difference; HTTP 403 is reserved for requests that fail because the
already authenticated user is not authorized (i.e. lacking permissions)
to do something.

tests/integration/api/Auth/AuthenticateWithApiKeyTest.php

@@ -63,7 +63,7 @@ class AuthenticateWithApiKeyTest extends TestCase
 
         $response = $api->send(CreateGroupController::class, new Guest);
 
-        $this->assertEquals(403, $response->getStatusCode());
+        $this->assertEquals(401, $response->getStatusCode());
     }
 
     /**