Fix function timeout for API endpoint

As described in 
netlify/next-on-netlify#66 (comment)

Author: FinnWoelm

pages/api/test.js

@@ -1,6 +1,20 @@
 import admin from "firebase-admin";
 
 const test = async (req, res) => {
+  // Get function context to avoid timeout
+  // See: https://github.com/netlify/next-on-netlify/issues/66#issuecomment-719988804
+  const functionContext = req?.functionContext;
+
+  // If we are currently in a Netlify function (deployed on netlify.app or
+  // locally with netlify dev), do not wait for empty event loop.
+  // See: https://stackoverflow.com/a/39215697/6451879
+  // Skip during next dev.
+  if (functionContext) {
+    console.log("Setting callbackWaitsForEmptyEventLoop: false");
+    functionContext.callbackWaitsForEmptyEventLoop = false;
+  }
+
+  // Initialize firebase app
   if (!admin.apps.length) {
     admin.initializeApp({
       credential: admin.credential.cert({