refactor: use JoinHostPort for vnc tcp dialing

Replace manual `"%s:%d"` address formatting with `net.JoinHostPort` when dialing VNC. This ensures host/port strings are constructed correctly (including IPv6 hosts) and avoids malformed TCP target addresses.

Signed-off-by: Ryan Johnson <ryan@tenthirtyam.org>

Author: tenthirtyam

builder/vmware/common/step_vnc_connect.go

@@ -46,7 +46,7 @@ func (s *StepVNCConnect) ConnectVNC(ctx context.Context, state multistep.StateBa
 	vncPort := state.Get("vnc_port").(int)
 	vncPassword := state.Get("vnc_password")
 
-	nc, err := net.Dial("tcp", fmt.Sprintf("%s:%d", vncIp, vncPort))
+	nc, err := net.Dial("tcp", net.JoinHostPort(vncIp, fmt.Sprintf("%d", vncPort)))
 	if err != nil {
 		err := fmt.Errorf("error connecting to VNC: %s", err)
 		state.Put("error", err)