fix: disable psiphon when building with go1.19 (#871)

Part of https://github.com/ooni/probe/issues/2211.

See also https://github.com/ooni/probe/issues/2222, which
describes the issue we have with psiphon and go1.19.

internal/tunnel/psiphon_integration_test.go

@@ -1,5 +1,11 @@
+//go:build !go1.19
+
 package tunnel_test
 
+//
+// Psiphon not working with go1.19: TODO(https://github.com/ooni/probe/issues/2222)
+//
+
 import (
 	"context"
 	"io/ioutil"