test: remove redundant assertion

Author: innocenzi

tests/Integration/Database/ModelsWithoutIdTest.php

@@ -356,7 +356,6 @@ public function test_load_method_refreshes_all_properties_not_just_relations():
         $this->assertSame('Frieren', $userInstance->name); // "Fern" was discarded here
         $this->assertSame('[email protected]', $userInstance->email);
         $this->assertInstanceOf(TestProfile::class, $userInstance->profile);
-        $this->assertNotNull($userInstance->profile->bio);
     }
 }