Medium Posts API migrated to Vercel hosting

[david-fernando]

Reason for change

• First: The-end free Heroku Dynos.
  Until the moment Medium Posts API used free Heroku Dynos, but with the end of it, or I started to charge for the service, or I migrated to another hosting.

• Second: Limitation of use.
  Heroku only gave me 550 free hours of Dynos when that limit ran out, service went down.
  Several times this limit ran out, and that's exactly why the applications that use it had no API access.

If you use our service, please update to the new address as soon as possible.
Without further ado, sorry for any issues the change causes, your support will be very important now!