updating the MYNN-EDMF (#2291)

Updating the pointer to MYNN-EDMF submodule

TYPE: bug fix

KEYWORDS: MYNN-EDMF downdraft

SOURCE: Joseph Olson

DESCRIPTION OF CHANGES:
Problem:
Two bugs were found by the new automated CI testing
One update to the mixing of anthropogenic aerosols was made recently.

Solution:
Update the pointer to the top of the MYNN-EDMF repository to bring in
the fixes/modifications

LIST OF MODIFIED FILES: list of changed files (use `git diff
--name-status develop` to get formatted list)
M       phys/MYNN-EDMF

TESTS CONDUCTED: 
1. Do mods fix problem? Yes
2. Are the Jenkins tests all passing?

Author: joeolson42