Support MappedAsDataclass

[Goradii]

fixed insertion error if MappedAsDataclass #737

BEFORE FIX 3.8

FAILED tests/test_sa2/test_view_sync.py::test_sync_create_dataclass - assert 0 == 1
FAILED tests/test_sa2/test_views_async.py::test_async_create_dataclass - assert 0 == 1
2 failed, 179 passed, 3 skipped, 7 warnings in 40.15s

AFTER FIX 3.8

181 passed, 3 skipped, 7 warnings in 41.22s

[mmzeynalli]

@Goradii can you check if latest version of sqladmin still have this problem? If yes, let me know

[Goradii]

Yes same issue 😞

py313

$ uv tree | grep sqladmin
Resolved 83 packages in 2ms
├── sqladmin v0.22.0