GEOS-Chem submod update: Merge PR #1998 (Rename YAML tags)

This commit informs the GCHP superproject about the following
commits that were pushed to the GitHub geos-chem/geos-chem repository:

66fb61ab1 Merge PR #1998 (Rename YAML tags for aerosol nitrate photolysis )

This PR renames the YAML tags controlling nitrate aerosol photolysis
in the geoschem_config.yml.fullchem to more accurately describe what
is being requested.  This is a zero-diff update but needs to go into
14.4.0 as it touches run-directory configg files.

Signed-off-by: Bob Yantosca <yantosca@seas.harvard.edu>