ES6 modules not working with Symfony Asset-Mapper

[wolfkidsounds]

I think this is related to #889

When using
import { Timeline } from '@knight-lab/timelinejs';
the Symfony Asset-Mapper uses jsDelivr to get the correct files.

However jsDelivr can not get the correct files and throws an error.
Therefore we get The requested module '@knight-lab/timelinejs' does not provide an export named 'Timeline'.

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I think solving the related issues should solve this situation too.

Thanks for the package, really loving it <3