Update .gitmodules

Co-authored-by: Gillian Petro <96886803+gspetro-NOAA@users.noreply.github.com>

Author: ClaraDraper-NOAA

.gitmodules

@@ -1,7 +1,7 @@
 [submodule "UFSATM"]
   path = UFSATM
   url = https://github.com/ClaraDraper-NOAA/ufsatm.git
-  branch = update-ufsatm-ccpp-physics-sfcsub-cleanup
+  branch = update-ccpp-physics-sfcsub-cleanup
 [submodule "WW3"]
   path = WW3
   url = https://github.com/NOAA-EMC/WW3