How to specify custom dist folder in electron-forge

I'm using yarn workspaces and my electron app is in packages/app All works well, apart when I run yarn start in packages/app it will produce dist folder in root not in desired pacakges/app. I tried to modify package.json in app and in root (just in case) but with no luck

"config": {
    "forge": {
      "packagerConfig": {
        "out": "packages/app/dist"
      }
    }
  }

just to make clear this is what I have

root
  |- dist
  |- packages (workspaces)
    |- app
    |  |- // I want dist here
    |
    |- module-b