chore(deps-dev): bump axios in /packages/opencensus-exporter-promethe…

…us (#909)

Bumps [axios](https://github.com/axios/axios) from 0.19.0 to 0.21.1.
- [Release notes](https://github.com/axios/axios/releases)
- [Changelog](https://github.com/axios/axios/blob/master/CHANGELOG.md)
- [Commits](axios/axios@v0.19.0...v0.21.1)

---
updated-dependencies:
- dependency-name: axios
  dependency-type: direct:development
...

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