Webpack can't resolve imported css files in custom pages.

[LiamAttClarke]

Bug report

Describe the bug

Importing a css file in a custom page no longer works with the latest release (@keystonejs/app-admin-ui v5.12.0).

To Reproduce

1. Create a custom page.
2. Import a local css file.
   Example:

import './CustomPage.css';

export default () => <div className="some-class"></div>;

3. Start Keystone and open in the browser.

Expected behaviour

The css file should be resolved by Webpack as it did in previous versions of app-admin-ui.

Screenshots

System information

• OS: Windows

Additional context

@Nikodermus Suggested this might be caused by his recent change (#2860). Perhaps this implicitly excludes local css file resolution?

[gautamsi]

this should be reverted and investigated on why the css from node_modules not included when there is no exclude option specified.

[MadeByMike]

Resolved in #2860