Issue with type hints in public API's

There are some exposed functions, such as `create_async_client` and `create_client` whose type signature has some hints which are considered mistakes from many tools:
```python
def create_client(
dsn=None,
*,
max_concurrency=None,
host: str = None,
port: int = None,
credentials: str = None,
credentials_file: str = None,
user: str = None,
password: str = None,
secret_key: str = None,
database: str = None,
branch: str = None,
tls_ca: str = None,
tls_ca_file: str = None,
tls_security: str = None,
wait_until_available: int = 30,
timeout: int = 10,
):
```
A type which is not `T | None` cannot be assigned `None`, which causes this flurry of lints:


All public API's of the client should conform to strict typing in python to avoid consumers of the client to have to hack around their linting & LSP tooling.

Start with the public create_client and create_async_client entry points named in the issue, then identify the other exposed client APIs with similar optional parameters. Check their signatures with strict typing and linting tools; done means public APIs no longer report errors for parameters that default to None.

索引モデルが issue の本文から書いたものです。