ResampleStep fails for custom wcs

[braingram]

Providing a custom wcs (in this case a wcs from a cal file) results in an exception:

from jwst.resample import ResampleStep
import asdf

# point this to the corresponding regtest file
cal_filename = "~/jwst-pipeline/dev/nircam/image/jw01069002001_01101_00001_nrca5_cal.fits"
m = dm.open(cal_filename)
wcs = m.meta.wcs
asdf.AsdfFile({"wcs": wcs}).write_to("custom_wcs.asdf")

step = ResampleStep(output_wcs="custom_wcs.asdf")
result = step(m)

Produces an exception:

Traceback (most recent call last):
  File "/Users/bgraham/projects/src/jwst/resample_to_cal.py", line 13, in <module>
    result = step(m)
             ^^^^^^^
  File "/Users/bgraham/projects/src/jwst/jwst/stpipe/core.py", line 159, in __call__
    return super().__call__(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/bgraham/.pyenv/versions/jwst/lib/python3.12/site-packages/stpipe/step.py", line 585, in __call__
    return self.run(*args)
           ^^^^^^^^^^^^^^^
  File "/Users/bgraham/projects/src/jwst/jwst/stpipe/core.py", line 141, in run
    result = super().run(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/bgraham/.pyenv/versions/jwst/lib/python3.12/site-packages/stpipe/step.py", line 507, in run
    step_result = self.process(*args)
                  ^^^^^^^^^^^^^^^^^^^
  File "/Users/bgraham/projects/src/jwst/jwst/resample/resample_step.py", line 123, in process
    result = resamp.resample_many_to_one()
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/bgraham/projects/src/jwst/jwst/resample/resample.py", line 621, in resample_many_to_one
    self.finalize()
  File "/Users/bgraham/projects/src/jwst/jwst/resample/resample.py", line 462, in finalize
    self.update_fits_wcsinfo(self.output_jwst_model)
  File "/Users/bgraham/projects/src/jwst/jwst/resample/resample.py", line 645, in update_fits_wcsinfo
    model.meta.wcsinfo.cdelt1 = transform[3].factor.value
                                ^^^^^^^^^^^^^^^^^^^
AttributeError: 'Shift' object has no attribute 'factor'

The exception occurs on jwst main (current commit 7545a60) and on 1.17.1 (no earlier versions were tested).