MAPG-199 fix issues found by PHPStan

tests/PersistentData/Model/ModelTest.php

@@ -3,6 +3,10 @@
 use MapGuesser\PersistentData\Model\Model;
 use PHPUnit\Framework\TestCase;
 
+class OtherModel
+{
+}
+
 class DummyModel extends Model
 {
     protected static string $table = 'test_table';