Add gmm_demux as hashing method

Author: bbimber

singlecell/api-src/org/labkey/api/singlecell/CellHashingService.java

@@ -281,6 +281,7 @@ public enum CALLING_METHOD
         multiseq(true),
         htodemux(false),
         dropletutils(true),
+        gmm_demux(true),
         bff_quantile(true),
         bff_threshold(false);