Bump prom-client from 14.2.0 to 15.1.2 (#507)

Bumps [prom-client](https://github.com/siimon/prom-client) from 14.2.0 to 15.1.2.
- [Release notes](https://github.com/siimon/prom-client/releases)
- [Changelog](https://github.com/siimon/prom-client/blob/master/CHANGELOG.md)
- [Commits](siimon/prom-client@v14.2.0...v15.1.2)

---
updated-dependencies:
- dependency-name: prom-client
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Jeremiah Uy <[email protected]>