Preparing for 1.6.20 release

Author: johanhaleby

kubetail

@@ -61,7 +61,7 @@ selector=()
 regex='substring'
 previous="${default_previous}"
 since="${default_since}"
-version="1.6.20-SNAPSHOT"
+version="1.6.20"
 dryrun=false
 cluster=""
 namespace_arg="-n ${default_namespace}"