action: fix incorrect -d flag

[lmb]

lvh images pull doesn't understand -d. The correct flag is --dir.

[lmb]

$ ./lvh images pull --help
Pull an image from an OCI repository

Usage:
  lvh images pull <URL> [flags]

Flags:
      --cache        cache a compressed version of the image
      --dir string   directory to keep the images (images will be saved in images in <dir>/images) (default "_data")
  -h, --help         help for pull

[kkourt]

So this never worked? 🤔