fix: support nohoist in yarn workspaces

[egilsster]

Fixes an issue where the workspaces property isnt an array in package.json as seen on https://classic.yarnpkg.com/blog/2018/02/15/nohoist/

Status

[ ] Under development
[ ] Waiting for code review
[x] Waiting for merge

Information

[ ] Contains breaking changes
[ ] Contains new API(s)
[ ] Contains documentation
[ ] Contains test

[coveralls]

Coverage remained the same at 32.496% when pulling 6fa1248 on workspaces into 1ae4d0b on v6.x.