[MM-56594] Upgrade from Node-18.10(Maintaince) to Node-20.11(LTS) (#26335)

.nvmrc

@@ -1 +1 @@
-18.17
+20.11

webapp/package-lock.json

@@ -46,7 +46,7 @@
         "webpack-dev-server": "4.13.3"
       },
       "engines": {
-        "node": "^18.10.0",
+        "node": ">=18.10.0",
         "npm": "^9.0.0 || ^10.0.0"
       }
     },

webapp/package.json

@@ -2,7 +2,7 @@
   "name": "@mattermost/webapp",
   "private": true,
   "engines": {
-    "node": "^18.10.0",
+    "node": ">=18.10.0",
     "npm": "^9.0.0 || ^10.0.0"
   },
   "scripts": {