fix bug: workflow input

workflow.wdl

@@ -174,7 +174,7 @@ workflow {{ project_name }} {
 			dbsnp=dbsnp,
 			dbsnp_dir=dbsnp_dir,
 			regions=regions,
-			docker=docker,
+			docker=sentieon_docker,
 			disk_size=disk_size,
 			cluster_config=cluster_config
 		}