`return_columns=True` for `FastCRUD.update(...)` errors in `TypeError: 'bool' object is not iterable`

[UnoYakshi]

Description
I was working on a patch to allow polymorphic inheritance. I stumbled upon fastcrud.crud.fast_crud::FastCRUD.update(...) with return_columns=True.

Inside of update(), there is a call of fastcrud.crud.execution.execute_update_and_return_response() that doesn't handle return_columns=True:

    if return_columns:
        stmt = stmt.returning(*[column(name) for name in return_columns])
        db_row = await db.execute(stmt)
        if commit:
            await db.commit()

        if allow_multiple:
            multi_data = [dict(row) for row in db_row.mappings()]
            formatted_data = format_multi_response(
                multi_data, schema_to_select, return_as_model
            )
            return {"data": formatted_data}

and I get an error:

>           stmt = stmt.returning(*[column(name) for name in return_columns])
                                                             ^^^^^^^^^^^^^^
E           TypeError: 'bool' object is not iterable

However, update()'s docstring says

return_columns: A list of column names to return after the update. If `return_as_model` is True, all columns are returned.

To Reproduce

import pytest

from fastcrud import FastCRUD
from pydantic import BaseModel

# conftest.py...
class Entity(Base):
    __tablename__ = 'entities'
    __mapper_args__ = {
        'polymorphic_on': 'type',
        'polymorphic_identity': 'entity',
        'with_polymorphic': '*',
    }
    id = Column(Integer, primary_key=True, autoincrement=True)
    type = Column(String(100), nullable=True, default='entity')


class UserEntity(Entity):
    __tablename__ = 'users_entities'
    __mapper_args__ = {
        'polymorphic_identity': 'user_entity',
    }
    id = Column(ForeignKey('entities.id'), primary_key=True)
    name = Column(String(100), nullable=True)


class UserEntityCreateSchema(BaseModel):
    name: str


# SQLAlchemy test...
@pytest.mark.asyncio
async def test_update_polymorphic(async_session):

    user = UserEntity(name="User A")
    async_session.add(user)
    await async_session.commit()
    await async_session.refresh(user)

    new_user_name = "Update User Name"
    new_raw_data = UserEntityCreateSchema(name=new_user_name)

    crud = FastCRUD(model=UserEntity)
    fetched_record = await crud.update(
        db=async_session,
        object=new_raw_data,
        return_as_db_obj=True,
        return_columns=True,
        id=user.id,
    )

    assert fetched_record is not None
    assert fetched_record.id == 1
    assert fetched_record.name == new_user_name
    assert fetched_record.type == "user_entity"