BAU: Upgrade TypeScript version and update Node engine

This dependency update is required to move to the newer version
of Helmet.

TypeScript version updated via `yarn upgrade typescript` which
requires a newer version of the Node engine. Have therefore also
updated the Node engine in the package.json to reflect the required
Node engine.

package.json

@@ -5,7 +5,7 @@
   "author": "",
   "license": "ISC",
   "engines": {
-    "node": "18.x"
+    "node": "18.20.*"
   },
   "scripts": {
     "build-ts": "tsc",

yarn.lock

@@ -5778,9 +5778,9 @@ typedarray-to-buffer@^3.1.5:
     is-typedarray "^1.0.0"
 
 typescript@^4.5.4:
-  version "4.5.4"
-  resolved "https://registry.npmjs.org/typescript/-/typescript-4.5.4.tgz"
-  integrity sha512-VgYs2A2QIRuGphtzFV7aQJduJ2gyfTljngLzjpfW9FoYZF6xuw1W0vW9ghCKLfcWrCFxK81CSGRAvS1pn4fIUg==
+  version "4.9.5"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.9.5.tgz#095979f9bcc0d09da324d58d03ce8f8374cbe65a"
+  integrity sha512-1FXk9E2Hm+QzZQ7z+McJiHL4NW1F2EzMu9Nq9i3zAaGqibafqYwCVU6WyWAuyQRRzOlxou8xZSyXLEN8oKj24g==
 
 uglify-js@^3.14.5:
   version "3.19.2"