GEOS-Chem submod update: Merge PR #2352 (ALK4/R4N2 fixes from J. Brewer)

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

0a392d465 Merge PR #2352 (Fixes for ALK4 and R4N2 chemistry from J. Brewer)

R4N2 was a common product of alkane, isoprene, and monoterpene oxidation
and produced organonitrate SOA but we don’t want ALK4 to produce
organonitrate SOA as discusses in #1625. A fix from Jared Brewer is
included in this PR.

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