chore(deps-dev): bump axios in /packages/opencensus-exporter-prometheus (#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
...

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]