[FEATURE] [BACKEND] leaderboard

[mosesokemwa]

Describe the user story:

Tasks (where applicable)

• [x] eg. Fetch users end point

Tests (where applicable)

• [ ] eg. Passing Tests for x

Acceptance Criteria

• [x] eg end-point " api/users" should not list users for non-admin users
• [x] eg end-point " api/users" should list users for admin users

Screenshots where applicable