Update included Node to latest LTS version

[jmorrell]

No description provided.

[schneems]

Thanks!

[luccasmaso]

@schneems Is there any reason from node version not be infered from node engine version inside package.json? Adding both ruby and node buildpacks to my app in Heroku causes yarn being called twice using a rails app with Webpacker (where the second time is called by rails assets:precompile).

I actually found out that rails/webpacker@386fd85
resolves the problem of yarn install invocation when assets precompile run. The problem is that only this last yarn install generates a manifest file for Webpacker. So, the yarn install from nodejs Buildpack is not enough relevant.

Webpacker can't find application in /app/public/packs/manifest.json. Possible causes:

Thanks