Update dependencies

vendor/tailscale.com/util/systemd/doc.go

@@ -0,0 +1,13 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+/*
+Package systemd contains a minimal wrapper around systemd-notify to enable
+applications to signal readiness and status to systemd.
+
+This package will only have effect on Linux systems running Tailscale in a
+systemd unit with the Type=notify flag set. On other operating systems (or
+when running in a Linux distro without being run from inside systemd) this
+package will become a no-op.
+*/
+package systemd