change hack shallow test grid to ne3pg3

Author: peverwhee

cime_config/testdefs/testlist_cam.xml

@@ -52,7 +52,7 @@
       <option name="comment">Test for Zhang McFarlane physics</option>
     </options>
   </test>
-  <test compset="FPHYStest" grid="ne5_ne5_mg37" name="SMS_Ln2" testmods="cam/outfrq_hack_shallow_derecho">
+  <test compset="FPHYStest" grid="ne3pg3_ne3pg3_mg37" name="SMS_Ln2" testmods="cam/outfrq_hack_shallow_derecho">
     <machines>
       <machine name="derecho" compiler="gnu" category="aux_sima"/>
     </machines>