Fix dependency in api-routes example

[TyMick]

Installing the api-routes example app currently fails with npm because its react^17.0.2 dependency conflicts with its swr@0.1.18 dependency, as the latter has a peer dependency on react^16.11.0. Here's what I'm seeing when I try to install with create-next-app:

$ create-next-app --example api-routes --use-npm
✔ What is your project named? … my-app-npm
Creating a new Next.js app in ~/temp/my-app-npm.

Downloading files for example api-routes. This might take a moment.

Installing packages. This might take a couple of minutes.

npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR! 
npm ERR! While resolving: undefined@undefined
npm ERR! Found: react@17.0.2
npm ERR! node_modules/react
npm ERR!   react@"^17.0.2" from the root project
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer react@"^16.11.0" from swr@0.1.18
npm ERR! node_modules/swr
npm ERR!   swr@"0.1.18" from the root project
npm ERR! 
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR! 
npm ERR! See ~/.npm/eresolve-report.txt for a full report.

npm ERR! A complete log of this run can be found in:
npm ERR!     ~/.npm/_logs/2021-09-17T14_36_51_070Z-debug.log

Aborting installation.
  npm install has failed.

This PR upgrades SWR to the latest version, ^1.0.1, after which its React peer dependency no longer conflicts, installation succeeds with npm, and the example app continues to function (no migration is necessary in this case).

Documentation / Examples

• Make sure the linting passes

[ijjk]

Thanks!