Bump prometheus from 0.13.4 to 0.14.0

Bumps [prometheus](https://github.com/tikv/rust-prometheus) from 0.13.4 to 0.14.0.
- [Changelog](https://github.com/tikv/rust-prometheus/blob/master/CHANGELOG.md)
- [Commits](tikv/rust-prometheus@v0.13.4...v0.14.0)

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

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

Author: dependabot[bot]

Cargo.lock

@@ -19,7 +19,7 @@ failure      = "0.1"
 lazy_static  = "1"
 hyper        = "0.12"
 interfaces   = "0.0.9"
-prometheus   = "0.13"
+prometheus   = "0.14"
 rand         = "0.9"
 serde        = {version = "1.0", features = ["derive"]}
 structopt    = "0.3"