fix: update listen and close deprecation warning message

Author: snitin315

lib/Server.js

@@ -2404,7 +2404,7 @@ class Server {
   listen(port, hostname, fn) {
     util.deprecate(
       () => {},
-      "'listen' is deprecated. Please use async 'start' or 'startCallback' methods.",
+      "'listen' is deprecated. Please use the async 'start' or 'startCallback' method.",
       "DEP_WEBPACK_DEV_SERVER_LISTEN"
     )();
 
@@ -2464,7 +2464,7 @@ class Server {
   close(callback) {
     util.deprecate(
       () => {},
-      "'close' is deprecated. Please use async 'stop' or 'stopCallback' methods.",
+      "'close' is deprecated. Please use the async 'stop' or 'stopCallback' method.",
       "DEP_WEBPACK_DEV_SERVER_CLOSE"
     )();