Use const for version string.

go-sendxmpp.go

@@ -24,6 +24,10 @@ import (
 	"github.com/pborman/getopt/v2" // BSD-3-Clause
 )
 
+const (
+	VERSION = "devel"
+)
+
 type configuration struct {
 	username string
 	jserver  string
@@ -254,7 +258,7 @@ func main() {
 
 	// If requested, show version and quit.
 	if *flagVersion {
-		fmt.Println("go-sendxmpp", "devel")
+		fmt.Println("go-sendxmpp", VERSION)
 		fmt.Println("License: BSD-2-clause")
 		os.Exit(0)
 	}