`opt_fields` for `get_tasks_for_project` is not returning additional fields

[hejhugo]

Description

The opt_fields parameter for the get_tasks_for_project method is not returning the specified additional fields. When using opt_fields to request custom fields, the response does not include these fields.

I think this is also related to #170, where options are not being passed to the API. The same call works in my Postman example but not with this Ruby gem.

[KostyaSha]

You need pass field into options because internally it adds opt_ prefix.