Theme Check should not warn users about `https://unpkg.com/@shopify/theme-hot-reload`

[karreiro]

Describe the bug

This script is used for infrastructure purposes and some developers may commit them like this:

{% if request.design_mode %}
  <script
    id="hot-reload-client"
    src="https://unpkg.com/@shopify/theme-hot-reload"
    defer
  ></script>
{% endif %}

Expected behaviour

The warning above shouldn't happen.

Actual behaviour

The warning above happens.