Support for vis-timeline >= 8

[Glandos]

vis-timeline >=8 introduces ESM, so the 'vis-timeline/esnext' is now broken.

I was able to (badly) patch vue2vis with yarn:

@vue2vis-timeline-npm-1.0.1-alpha.78-9cbd815c10.patch

@vue2vis-utils-npm-1.0.1-alpha.86-40c04407dc.patch

But this is rather crude to me…