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/google.golang.org/appengine/internal/main_vm.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed by the Apache 2.0
 // license that can be found in the LICENSE file.
 
+//go:build !appengine
 // +build !appengine
 
 package internal
@@ -29,7 +30,7 @@ func Main() {
 	if IsDevAppServer() {
 		host = "127.0.0.1"
 	}
-	if err := http.ListenAndServe(host+":"+port, http.HandlerFunc(handleHTTP)); err != nil {
+	if err := http.ListenAndServe(host+":"+port, Middleware(http.DefaultServeMux)); err != nil {
 		log.Fatalf("http.ListenAndServe: %v", err)
 	}
 }