Nifti saving function not working

[alinafdima]

https://github.com/BioMedIA/deepali/blob/ae3e4762a20cbbd0711cc5dd53a7f1aafad49b86/src/deepali/utils/imageio/nifti.py#L116

The Nifti saving function using nibabel here does not work because the affine matrix is incomplete. The output affine matrix from grid.affine() is 3x3 which is missing the origin/translation required for nibabel.