Deprecation warning with ember-cli-sass

[ntodd]

DEPRECATION WARNING on line 1, column 8 of /ember-app/tmp/sass_compiler-input_base_path-xAOqyt5U.tmp/app/styles/app.scss:
Including .css files with @import is non-standard behaviour which will be removed in future versions of LibSass.
Use a custom importer to maintain this behaviour. Check your implementations documentation on how to create a custom importer.

// app.scss
@import 'pod-styles';

ember-cli: 3.1.4
ember: 3.1.2
ember-cli-sass: 7.1.7
node-sass: 4.9.0