Fix function without prototype

I'm not sure why this is considered a function without prototype, but in
C function without arguments accept any number of arguments. In this
case we want a function that does not accept arguments so we need to use
(void).

    cli.c:64:26: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
       64 | static void print_version() { puts(VERSION); }
          |                          ^
          |                           void

Signed-off-by: Nir Soffer <[email protected]>

Author: nirs

cli.c

@@ -61,7 +61,7 @@ static void print_usage(const char *argv0) {
   printf("version: " VERSION "\n");
 }
 
-static void print_version() { puts(VERSION); }
+static void print_version(void) { puts(VERSION); }
 
 enum {
     CLI_OPT_SOCKET_GROUP = CHAR_MAX + 1,