Bump next from 9.1.3 to 9.3.2 in /examples/nextjs-app (#332)

Bumps [next](https://github.com/zeit/next.js) from 9.1.3 to 9.3.2.
- [Release notes](https://github.com/zeit/next.js/releases)
- [Commits](vercel/next.js@v9.1.3...v9.3.2)

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