Hi,

First of all, thank you for the great library @ankane!

I'm opening this PR to address some issues that have been raised by users (#84, #110 and #112), that is to input types other than string in the BIT SQLAlchemy model (also when using the asyncpg dialect). In brief with this PR, given:

class Item(Base):
    id = mapped_column(Integer, primary_key=True)
    binary_embedding = mapped_column(BIT(3))

You can add it to your database using whatever input you like (and this will be transformed following the logic already present in the init of the Bit class):

with Session(engine) as session: 
   session.add(Item(id = 1, 
   binary_embedding = [True, False, True])) # or [1, 0, 1], or np.array([1, 0, 1])