Calendar API

[RoBizMan]

As a user, I can view the availability date so that I can book a tutoring session as soon as it is available as per the calendar.

Acceptance Criteria:

• Implement a calendar API.
• A user can book a tutoring service based on availability through a calendar API.
• The booking can be completed through a calendar API and a Stripe payment.
• Once the tutoring service is booked, the availability date becomes unavailable once it is booked to prevent users from booking the unavailable date.