Refactor a named return

Ref: https://github.com/Jguer/yay/pull/601/files/29f3e011eca4063635d4182a609f5e3b404a4e7d#diff-0cf3d18277fde705f1a4eb69fddfefc1L407

cmd.go

@@ -396,7 +396,7 @@ func handleYogurt() error {
 	return numberMenu(cmdArgs.targets)
 }
 
-func handleSync() (err error) {
+func handleSync() error {
 	targets := cmdArgs.targets
 
 	if cmdArgs.existsArg("s", "search") {