GEOS-Chem submod update: Merge PR #2226 (Fix bug for ST80_25 tracer)

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

d085e39ce Merge PR #2226 (Fix bug in pressure mask affecting ST80_25 tracer)

This PR fixes an issue in how ST80_25 (a species used in the
TransportTracers simulation) is computed.

Signed-off-by: Bob Yantosca <[email protected]>