`cfa` script fails when using the `-d` option

[davidhassell]

$ cfa -d tmp_dir test1.nc
Traceback (most recent call last):
  File "/home/david/cf-python/scripts/./cfa", line 1499, in <module>
    if write_options["cfa"]:
KeyError: 'cfa'
$

>>> import cf
>>> cf.environment(paths=False)
Platform: Linux-5.15.0-71-generic-x86_64-with-glibc2.35
HDF5 library: 1.14.0
netcdf library: 4.9.2
udunits2 library: /home/david/miniconda3/lib/libudunits2.so.0
esmpy/ESMF: not available
Python: 3.10.10
dask: 2023.3.1
netCDF4: 1.6.3
psutil: 5.9.5
packaging: 23.1
numpy: 1.22.1
scipy: 1.10.1
matplotlib: 3.7.1
cftime: 1.6.2
cfunits: 3.3.6
cfplot: 3.2.7
cfdm: 1.10.1.0
cf: 3.15.0