stamp 0.2.1: remove unneeded opentelemetry dependency

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "tower-otel-http-metrics"
 edition = "2021"
-version = "0.2.0"
+version = "0.2.1"
 license = "MIT"
 description = "OpenTelemetry Metrics Middleware for Tower-compatible Rust HTTP servers"
 homepage = "https://github.com/francoposa/tower-otel-http-metrics"
@@ -19,7 +19,6 @@ axum = { features = ["matched-path"], version = "0.7", default-features = false,
 futures-core = { version = "0.3", default-features = false }
 futures-util = { version = "0.3", default-features = false }
 http = { version = "1", features = ["std"], default-features = false }
-opentelemetry = { version = "0.21", default-features = false }
 opentelemetry_api = { version = "0.20", features = ["metrics"], default-features = false }
 pin-project-lite = { version = "0.2", default-features = false }
 tower = { version = "0.4", default-features = false }