implement sign in with github

## Description

As a developer,
I need to add login with GitHub feature to app,
so that I can allow users to use their GitHub OAuth.

Implement login with GitHub to mentorship system

https://docs.github.com/en/developers/apps/building-oauth-apps/authorizing-oauth-apps

## Acceptance Criteria
### Update [Required]
- [ ] A user is able to login into the platform with GitHub OAuth

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

## Estimation

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