v0.3.0: Update prometheus requirement from 0.13.4 to 0.14.0 (#3)

* Update prometheus requirement from 0.13.4 to 0.14.0

Updates the requirements on [prometheus](https://github.com/tikv/rust-prometheus) to permit the latest version.
- [Changelog](https://github.com/tikv/rust-prometheus/blob/master/CHANGELOG.md)
- [Commits](https://github.com/tikv/rust-prometheus/compare/v0.13.4...v0.14.0)

---
updated-dependencies:
- dependency-name: prometheus
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

* Bump version number

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: David Cook <dcook@divviup.org>