I get the error below. How can I find out what the issue is? I've tried running this command from the Heroku website's terminal, and I still get the same error

unable to get local issuer certificate

when running the command

heroku run knex migrate:latest --app my-app

This is my Knex config

require('dotenv').config();

module.exports = {
  development: {
    client: 'pg',
    connection: {
      host: '127.0.0.1',
      user: 'postgres',
      password: '1234',
      database: 'samushao',
    },
  },
  production: {
    client: 'pg',
    connection: process.env.DATABASE_URL + "?sslmode=require",
    migrations: { tableName: 'knex_migrations' },
  },
};