[Feature Request] Upgrade npx

[michaeljota]

This is related to #114. But instead of installing npx with a certain npm version, I think it would be nice if this can be used to upgrade npx as well. npx versions are being develop more quickly than npm and this tool, as I see it, is the de facto to upgrade npm on Windows. So, I think it's natural if this could upgrade npx as well.

Thanks!