Remove dublicate db env vars

Author: agnetemoos

.env.example

@@ -62,12 +62,6 @@ CICERO_URL=CICERO_SERVER_HERE
 # Validator for citizen login API
 CITIZEN_LOGIN_API_VALIDATOR=system.utils.always_validate_citizen
 
-# Username for PostgreSQL
-POSTGRES_USER=bpc
-
-# Password for PostgreSQL
-POSTGRES_PASSWORD=bpc
-
 # Uncomment if you do not want Django behind a proxy
 USE_X_FORWARDED_HOST = True
 SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https')