title: Run another yarn/npm task within a package.json, without specifying yarn or npm
body: <p>I have a task in my package.json "deploy", which needs to first call "build". I have specified it like this:</p>
  
  <blockquote>
    <p>"deploy": "yarn run build; ./deploy.sh",</p>
  </blockquote>
  
  <p>The problem is that this hard codes <code>yarn</code> as the package manager. So if someone doesn't use <code>yarn</code>, it doesn't work. Switching to <code>npm</code> causes a similar issue.</p>
  
  <p>What's a good way to achieve this while remaining agnostic to the choice of <code>npm</code> or <code>yarn</code>?</p>