build(deps): update opentelemetry-otlp requirement from 0.14.0 to 0.15.0

Updates the requirements on [opentelemetry-otlp](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@v0.14.0...v0.15.0)

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

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

Cargo.toml

@@ -45,7 +45,7 @@ opentelemetry = { version = "0.21.0", features = ["trace", "metrics"] }
 opentelemetry_sdk = { version = "0.21.0", default-features = false, features = ["trace", "rt-tokio"] }
 opentelemetry-jaeger = "0.20.0"
 opentelemetry-stdout = { version = "0.2.0", features = ["trace", "metrics"] }
-opentelemetry-otlp = { version = "0.14.0", features = ["metrics"] }
+opentelemetry-otlp = { version = "0.15.0", features = ["metrics"] }
 opentelemetry-semantic-conventions = "0.13.0"
 futures-util = { version = "0.3", default-features = false }
 tokio = { version = "1", features = ["full"] }