[FIX]: Coupons controller get API returning empty array

[bhavyaj12]

Describe the bug
When fetching the coupons using the api, coupons object is empty despite adding coupons in db, as the db is not imported in the server.js file

To Reproduce
Steps to reproduce the behavior:

1. Using mockman can check that the GET api - "api/coupon" returns empty

Expected behavior
An array of coupons should be returned instead.

Screenshots

• Before fix

• After fix (as per my coupons.db)

Desktop (please complete the following information):

• OS: Windows 10
• Browser: Chrome
• Version: Chrome Version 102.0.5005.115 (Official Build) (64-bit)