chore(deps): bump metrics from 0.20.1 to 0.21.1

Bumps [metrics](https://github.com/metrics-rs/metrics) from 0.20.1 to 0.21.1.
- [Changelog](https://github.com/metrics-rs/metrics/blob/main/release.toml)
- [Commits](metrics-rs/metrics@metrics-v0.20.1...metrics-v0.21.1)

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

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

Author: dependabot[bot]

Cargo.lock

@@ -61,7 +61,7 @@ hyper = "0.14"
 ipfs-api = { version="0.17.0", features = ["with-hyper"] }
 ipfs-api-backend-hyper = { version="0.6.0", features = ["with-send-sync"] }
 mailgun-rs = "0.1.5"
-metrics = "0.20"
+metrics = "0.21"
 metrics-exporter-prometheus = "0.11"
 metrics-util = { version = "0.15", default-features = true }
 mime = "0.3"