Upgrade golang.org/x/crypto for ACME protocol v2

I also added the ACME directory URL to the log message, so that it can
be verified to be the v2 URL (and not the deprecated v1 URL).

This fixes T71444.

httpserver/httpserver.go

@@ -62,9 +62,10 @@ func New(config flamenco.Conf, handler http.Handler) Server {
 
 	case config.ACMEDomainName != "":
 		logrus.WithFields(logrus.Fields{
-			"acme_domain_name": config.ACMEDomainName,
-			"listen":           config.Listen,
-			"listen_https":     config.ListenHTTPS,
+			"acme_domain_name":   config.ACMEDomainName,
+			"listen":             config.Listen,
+			"listen_https":       config.ListenHTTPS,
+			"acme_directory_url": autocert.DefaultACMEDirectory,
 		}).Info("creating ACME/Let's Encrypt enabled server")
 		mgr := autocert.Manager{
 			Prompt:     autocert.AcceptTOS,