title: Dialect needs to be explicitly supplied as of v4.0.0
body: <p>I have been working on a NodeJS project which uses PostgreSQL database. 
  I am trying to implement migration to the database. Also, using Sequelize. After setting up the migration folder and config, it throws error while running db:migrate</p>
  
  <p>The error is:
  "Dialect needs to be explicitly supplied as of v4.0.0"</p>