Bump prometheus from 0.12.0 to 0.13.0 (#1415)

Bumps [prometheus](https://github.com/tikv/rust-prometheus) from 0.12.0 to 0.13.0.
- [Release notes](https://github.com/tikv/rust-prometheus/releases)
- [Changelog](https://github.com/tikv/rust-prometheus/blob/master/CHANGELOG.md)
- [Commits](tikv/rust-prometheus@v0.12.0...v0.13.0)

---
updated-dependencies:
- dependency-name: prometheus
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

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

telemetry/Cargo.toml

@@ -19,5 +19,5 @@ crossbeam-channel        = "0.5.1"
 once_cell                = "1.8.0"
 opentelemetry            = "0.15.0"
 opentelemetry-prometheus = "0.8.0"
-prometheus               = "0.12.0"
+prometheus               = "0.13.0"
 rouille                  = "3.3.0"