Update prometheus requirement from 0.13 to 0.14

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](tikv/rust-prometheus@v0.13.0...v0.14.0)

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

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

Author: dependabot[bot]

Cargo.toml

@@ -46,7 +46,7 @@ opentelemetry_sdk = { version = "0.28", optional = true, features = [
   "metrics",
   "rt-tokio-current-thread",
 ] }
-prometheus = { version = "0.13", default-features = false, optional = true }
+prometheus = { version = "0.14", default-features = false, optional = true }
 serde = "1.0"
 tracing = { version = "0.1.41", optional = true }