Add GitHub Oauth registration and login

## Description

As a developer,
I need to implement GitHub sign on,
so that I can allow GitHub users to login using their GitHub account.

For being able to use the application, the user has to create a new account and confirm the email just to login. It's a long process. So by having GitHub OAuth we can make the process shorter for users who have a GitHub account.

## Acceptance Criteria
### Update [Required]
- [ ] Implement GitHub OAuth login and registration
- [ ] Write unit tests for the updates ^^

## Definition of Done
- [ ] All of the required items are completed.
- [x] Approval by 1 mentor.

## Estimation
8 hours