all: use any instead of interface{}

My favorite part of generics.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>

net/portmapper/disabled_stubs.go

@@ -15,7 +15,7 @@ import (
 	"inet.af/netaddr"
 )
 
-type upnpClient interface{}
+type upnpClient any
 
 type uPnPDiscoResponse struct{}
 

net/portmapper/igd_test.go

@@ -67,7 +67,7 @@ func NewTestIGD(logf logger.Logf, t TestIGDOptions) (*TestIGD, error) {
 		doPCP:  t.PCP,
 		doUPnP: t.UPnP,
 	}
-	d.logf = func(msg string, args ...interface{}) {
+	d.logf = func(msg string, args ...any) {
 		// Don't log after the device has closed;
 		// stray trailing logging angers testing.T.Logf.
 		if d.closed.Get() {