novu-python fails to parse response from setting push notification provider credentials

[danbim]

Describe the bug
The current implementation has a bug that causes unexpected behavior under specific circumstances. This issue needs to be addressed to ensure the application functions reliably in all scenarios.
To Reproduce
Steps to reproduce the behavior:
Call SubscriberApi().credentials(user_id, provider_id, webhook_url, device_tokens) with empty webhook_url but with device_tokens and provider_id='apns' (for example) in order to set up push notifications. The request on server side will succeed but parsing the response will fail with:

TypeError: SubscriberChannelSettingsCredentialsDto.__init__() missing 2 required positional arguments: 'webhook_url' and 'channel'

Expected behavior
Call succeeds and successfully parses response of type SubscriberDto.

Screenshots
[Attach relevant screenshots, if available, to provide visual context for the issue.]

Versions (please complete the following information):

• Novu version: SaaS
• Python version: 3.11.4
• Novu-python version: 1.9.1

Additional context

Note to Reviewers:
I believe the fix is to make webhook_url and channel optional which makes sense to me as they won't be set if I only set up a push provider.

@dataclasses.dataclass
class SubscriberChannelSettingsCredentialsDto(CamelCaseDto["SubscriberChannelSettingsCredentialsDto"]):
    """Credentials payload for the specified provider."""

    webhook_url: Optional[str] = None
    """Webhook url used by chat app integrations. The webhook should be obtained from the chat app provider"""

    channel: Optional[str] = None
    """Channel specification for Mattermost chat notifications"""

    device_tokens: Optional[List[str]] = None
    """Contains an array of the subscriber device tokens for a given provider. Used on Push integrations"""