Update README.md to use "@use" instead of "@import"

[EatonZ]

trafficstars

@import is being deprecated so it's time to recommend the use of @use instead.

Unfortunately, just replacing @import with @use results in build errors, so I am not sure if changes need to be made to the project, or if the syntax needs to be slightly changed. I tried using sass-migrator, but it had nothing to say/migrate.😒

[EatonZ]

Any thoughts on this yet?

[mjabbink]

@vpicone thoughts?