[BUG] deploy fail when using `--build-arg`

[vanenshi]

here is the error log:

 # liara deploy --build-arg='staging=1'

App: client
Path: /Users/vanenshi/Work/client-website
Platform: docker
Port: 80
Disks: 
  next-cache -> /app/.next/cache
Compressed size: 12.65MB (use .gitignore to reduce the size)
✔ Upload finished.

 ›   Error: CODE 400: child "build" fails because [child "args" fails because ["args" must be an object]]