bugfix: candidate_id should be a string

[xiaoronglv]

Problem:

Based on the documentation, the candidate_id attribute of the report model should be a string. This gem using alias method to delegate candidate_id to the candidate object, which is a json object.

it caused errors.

# How to reproduce it?
response = Checkr::Report.retrieve(report_id)
response.candidate_id

Changes

explicitly define the method to access the candidate_id

reference

https://docs.checkr.com/#operation/getReport

[xiaoronglv]

Hi @akshay-8d66 , could you please help to review my code when you get the time?

[akshay-8d66]

This makes sense to me. Could you look into the failing tests. Happy to help if it's unclear.