Fix extended_printer_type migration

The change looks innocent, right?
The problem is, 0 and 2 are of type int (4 B).
This resulted in crash in load_item,
because there is a check for data size.

BFW-5938

src/persistent_stores/store_instances/config_store/migrations.cpp

@@ -162,7 +162,7 @@ namespace migrations {
 
         static_assert(extended_printer_type_model[0] == PrinterModel::mk4);
         static_assert(extended_printer_type_model[2] == PrinterModel::mk3_9);
-        backend.save_migration_item(journal::hash("Extended Printer Type"), has_400_motors ? 0 : 2);
+        backend.save_migration_item<uint8_t>(journal::hash("Extended Printer Type"), has_400_motors ? 0 : 2);
     }
 #endif