Fix infinite-hang bug in /api/uploadLayerImage

Oops, Next.js has built-in request body parsing that happens automatically. So it was giving us a `req.body` string, and our code to read in the body and put it in a buffer was waiting forever!

Thankfully, it's much easier than I expected to turn that behavior off for just one route. Now it works like before, so our existing code works again, ta da!

pages/api/uploadLayerImage.js

@@ -177,4 +177,10 @@ async function handleWithBeeline(req, res) {
   );
 }
 
+export const config = {
+  api: {
+    bodyParser: false,
+  },
+};
+
 export default handleWithBeeline;