Fix with-joi example (#62877)

## What?

`next-connect` signature has changed so the example failed to run.

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### What?

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Closes NEXT-2712

examples/with-joi/pages/api/people.js

@@ -1,14 +1,23 @@
 import Joi from "joi";
-import connect from "next-connect";
+import { createRouter } from "next-connect";
 import { validate } from "../../server/api/middlewares/validate";
 
+const router = createRouter();
+
 const personSchema = Joi.object({
   age: Joi.number().required(),
   name: Joi.string().required(),
 });
 
-export default connect().post(validate({ body: personSchema }), (req, res) => {
+router.post(validate({ body: personSchema }), (req, res) => {
   const person = req.body;
 
   return res.status(201).json({ data: person });
 });
+
+export default router.handler({
+  onError: (err, req, res) => {
+    console.error(err.stack);
+    res.status(err.statusCode || 500).end(err.message);
+  },
+});

examples/with-joi/pages/api/people/[id].js

@@ -1,8 +1,9 @@
 import Joi from "joi";
-import connect from "next-connect";
+import { createRouter } from "next-connect";
 import { validate } from "../../../server/api/middlewares/validate";
 
-export default connect().get(
+const router = createRouter();
+router.get(
   validate({
     query: Joi.object({
       id: Joi.string().uuid().required(),
@@ -18,3 +19,10 @@ export default connect().get(
     });
   },
 );
+
+export default router.handler({
+  onError: (err, req, res) => {
+    console.error(err.stack);
+    res.status(err.statusCode || 500).end(err.message);
+  },
+});