refactor(mockserviceworker.js): replace math.random with crypto.rando…

…muuid in service worker file

It's known that Math.Random isn't secure (see https://v8.dev/blog/math-random). Even if this file
isn't supposed to be deployed in production, some static code analysis tools may flag this as a
critical issue, breaking CI pipelines.

src/mockServiceWorker.js

@@ -112,7 +112,7 @@ self.addEventListener('fetch', function (event) {
   }
 
   // Generate unique request ID.
-  const requestId = Math.random().toString(16).slice(2)
+  const requestId = crypto.randomUUID().slice(0, 8)
 
   event.respondWith(
     handleRequest(event, requestId).catch((error) => {