Update yargs dev-dependency to latest version

[jfaltermeier]

Bug Description:

We are keeping the yargs devDependency back because of a compile issue in a script we are using (update-checksum.ts). We should fix the script so that can update yargs again

See https://github.com/eclipse-theia/theia-blueprint/pull/192 as well for the commit that fixes the yargs version

[jfaltermeier]

Also check whether the compile issue might be a result of yargs and @types/yargs not being in sync, because of a recent yargs update that was not yet picked up by the types package.