Bump axios from 0.18.0 to 0.18.1 in /demo

Bumps [axios](https://github.com/axios/axios) from 0.18.0 to 0.18.1.
- [Release notes](https://github.com/axios/axios/releases)
- [Changelog](https://github.com/axios/axios/blob/v0.18.1/CHANGELOG.md)
- [Commits](axios/axios@v0.18.0...v0.18.1)

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