TUN-8052: Update go to 1.21.5

Also update golang.org/x/net and google.golang.org/grpc to fix vulnerabilities,
although cloudflared is using them in a way that is not exposed to those risks

vendor/github.com/cespare/xxhash/v2/xxhash_asm.go

@@ -0,0 +1,15 @@
+//go:build (amd64 || arm64) && !appengine && gc && !purego
+// +build amd64 arm64
+// +build !appengine
+// +build gc
+// +build !purego
+
+package xxhash
+
+// Sum64 computes the 64-bit xxHash digest of b.
+//
+//go:noescape
+func Sum64(b []byte) uint64
+
+//go:noescape
+func writeBlocks(d *Digest, b []byte) int