Set correct npm version, use latest vscode extension versions

[danieldietrich]

Avoid #449 when using Gitpod by setting node version v14 aka lts/fermium (currently npm version 6.14.18)

@planger however ... I understand that it does not really fix the original issue of supporting newer node/npm versions. this is just a quick fix to be able to contribute to the current site

[planger]

Thanks @danieldietrich! This change looks good to me and I'm happy to approve!

However, I think we should keep #449 to track the task of supporting more current node versions.
Also, I think we should mention in the readme that building locally requires node 14.x.

Thank you!

[danieldietrich]

Thank you for the quick reply @planger!

(...) we should keep #449 to track the task of supporting more current node versions.

That makes absolutely sense to me!

(...) we should mention in the readme that building locally requires node 14.x

Yep, I've missed that. I've added another commit.
Please let me know if something needs to be changed or rephrased.

Thank you Philip & have a nice weekend

[danieldietrich]

@planger I recognized that the package-lock.json changed in my GitPod workspace. Do you always commit it? In that case I would add another commit before this PR is merged. Thanks!

[planger]

Thank you very much for the fast turnaround! I just made a suggestion to mention that ignoring peer dependency conflicts works too.

I think it would make sense to commit the modified package-lock.json. Thank you!

[danieldietrich]

Great! All changes are in place now.