Create Get request APi

[SalehMohammadMusa]

As a developer
I need to implement a read API for customer accounts
So that I can retrieve customer details via the microservice

Details and Assumptions

• The database schema for customer data already exists
• The microservice is built with Flask

Acceptance Criteria

Given a customer with ID 1 exists
When I send a GET request to `/customers/1`
Then I receive the customer's details in the response

Given a customer with ID 999 does not exist
When I send a GET request to `/customers/999`
Then I receive a 404 error response