fix: do not omit empty scope list on client grant

[mbelang]

The auth0 management requires at least an empty list: https://auth0.com/docs/api/management/v2#!/Client_Grants/post_client_grants

[jasonkuhrt]

IIUC this will fix alexkappa/terraform-provider-auth0#50 (comment). If so, 💯

[mbelang]

@alexkappa Can you review please? :)

[alexkappa]

I've given it a look and I think this is good merged. Normally, removing the omitempty would make it difficult to execute PATCH requests without setting the field (otherwise it will be wiped). But in this case, it seems the schema only allows for the scope field when PATCHing anyway so it makes sense to make this change.

Thanks for giving it a go @mbelang!

[mbelang]

Thanks a lot :)