How to add an environment variable with letters and numbers combined in docker-compose.yml?

I am trying to setup my stack and while I am using this:

version: '3.4'
 services:
  .
  .
  .
  db:
    image: "mcr.microsoft.com/mssql/server"
    environment:
      - SA_PASSWORD: MyPassword001
      - ACCEPT_EULA: Y
    ports:
      - "1433:1433"

I am getting this error:

ERROR: The Compose file ‘./docker-compose.yml’ is invalid because:services.db.environment contains {“SA_PASSWORD”: “MyPassword001”}, which is an invalid type, it should be a string

Is it possible to use such value for an environment variable in docker?

Source: StackOverflow