Update opentelemetry requirement from 0.19 to 0.20

Updates the requirements on [opentelemetry](https://github.com/open-telemetry/opentelemetry-rust) to permit the latest version.
- [Release notes](https://github.com/open-telemetry/opentelemetry-rust/releases)
- [Commits](open-telemetry/opentelemetry-rust@v0.19.0...v0.19.0)

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

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

Cargo.toml

@@ -62,7 +62,7 @@ openssl = "0.10"
 opentelemetry-http = { version = "0.8", default-features = false }
 opentelemetry-semantic-conventions = { version = "0.11", default-features = false }
 opentelemetry-prometheus = { version = "0.12", default-features = false }
-opentelemetry = { version = "0.19", default-features = false }
+opentelemetry = { version = "0.20", default-features = false }
 parking_lot = "0.12"
 path-slash = "0.2"
 percent-encoding = "2"