update depth

tasks/depth.wdl

@@ -8,7 +8,7 @@ task depth {
 	String disk_size
 	
 	command <<<
-		/opt/conda/bin/samtools depth -b ${bed} ${bam} > ${sample_id}.depth
+		/opt/conda/bin/samtools depth -a -b ${bed} ${bam} > ${sample_id}.depth
 	>>>
 
 	runtime {