fix(dhcp): can not renew an ip address

The dhcp server is systemd-networkd, and the dhcp
plugin can request an ip but can not renew it.
The systemd-networkd just ignore the renew request.

```
2024/09/14 21:46:00 no DHCP packet received within 10s
2024/09/14 21:46:00 retrying in 31.529038 seconds
2024/09/14 21:46:42 no DHCP packet received within 10s
2024/09/14 21:46:42 retrying in 63.150490 seconds
2024/09/14 21:47:45 98184616c91f15419f5cacd012697f85afaa2daeb5d3233e28b0ec21589fb45a/iot/eth1: no more tries
2024/09/14 21:47:45 98184616c91f15419f5cacd012697f85afaa2daeb5d3233e28b0ec21589fb45a/iot/eth1: renewal time expired, rebinding
2024/09/14 21:47:45 Link "eth1" down. Attempting to set up
2024/09/14 21:47:45 98184616c91f15419f5cacd012697f85afaa2daeb5d3233e28b0ec21589fb45a/iot/eth1: lease rebound, expiration is 2024-09-14 22:47:45.309270751 +0800 CST m=+11730.048516519
```

Follow the https://datatracker.ietf.org/doc/html/rfc2131#section-4.3.6,
following options must not be sent in renew

- Requested IP Address
- Server Identifier

Since the upstream code has been inactive for 6 years,
we should switch to another dhcpv4 library.
The new selected one is https://github.com/insomniacslk/dhcp.

Signed-off-by: Songmin Li <lisongmin@protonmail.com>

vendor/github.com/u-root/uio/rand/random_std.go

@@ -0,0 +1,32 @@
+// Copyright 2020 the u-root Authors. All rights reserved
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build plan9 || windows
+// +build plan9 windows
+
+package rand
+
+import (
+	"context"
+	"crypto/rand"
+)
+
+var defaultContextReader = &cryptoRandReader{}
+
+type cryptoRandReader struct{}
+
+// ReadContext implements a cancelable read.
+func (r *cryptoRandReader) ReadContext(ctx context.Context, b []byte) (n int, err error) {
+	ch := make(chan struct{})
+	go func() {
+		n, err = rand.Reader.Read(b)
+		close(ch)
+	}()
+	select {
+	case <-ctx.Done():
+		return 0, ctx.Err()
+	case <-ch:
+		return n, err
+	}
+}