Adjustment to support Databases and SQLAlchemy 2.0

[mes5k]

I tried using fastapi-pagination on a FastAPI + Databases project where I ran databases version 0.9.0 with SQLAlchemy > 2.0.

This line fails: https://github.com/uriyyo/fastapi-pagination/blob/main/fastapi_pagination/ext/databases.py#L30

select([func.count()]) needs to become select(func.count()) (i.e. remove brackets) for SQLAlchemy 2.0.

I'm not sure how you want to handle compatibility with different versions of SQLAlchemy, otherwise I would have created a PR.