Fix and test code against newer versions of nibabel

[mvdoc]

The newer version of nibabel (4.0) introduced some deprecation errors. We need to test our code against this newer version and fix the code that fails.

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----> 1 cortex.freesurfer.import_subj("subj01")

File ~/.local/lib/python3.8/site-packages/cortex/freesurfer.py:206, in import_subj(fs_subject, cx_subject, freesurfer_subject_dir, whitematter_surf)
    204         pts, polys, _ = get_surf(fs_subject, hemi, fsname, freesurfer_subject_dir=freesurfer_subject_dir)
    205         fname = str(surfs.format(subj=cx_subject, name=name, hemi=hemi))
--> 206         formats.write_gii(fname, pts=pts + surfmove, polys=polys)
    208 for curv, info in dict(sulc="sulcaldepth", thickness="thickness", curv="curvature").items():
    209     lh, rh = [parse_curv(curvs.format(hemi=hemi, name=curv)) for hemi in ['lh', 'rh']]

File ~/.local/lib/python3.8/site-packages/cortex/formats.pyx:193, in cortex.formats.write_gii()

File ~/.local/lib/python3.8/site-packages/nibabel/deprecator.py:181, in Deprecator.__call__.<locals>.deprecator.<locals>.deprecated_func(*args, **kwargs)
    178 @functools.wraps(func)
    179 def deprecated_func(*args, **kwargs):
    180     if until and self.is_bad_version(until):
--> 181         raise error_class(message)
    182     warnings.warn(message, warn_class, stacklevel=2)
    183     return func(*args, **kwargs)

ExpiredDeprecationError: from_array method is deprecated. Please use GiftiDataArray constructor instead.

* deprecated from version: 2.1
* Raises <class 'nibabel.deprecator.ExpiredDeprecationError'> as of version: 4.0

Originally posted by @mingxue1204 in #469 (comment)