Switch from the chrono clock feature to now (#1569)

In #1192, chrono was added as a dependency of the opentelemetry-stdout crate in order to support outputting timestamps in human readable format.

In that PR, all Chrono features were disabled apart from the clock feature.

However, since that change landed, chrono v0.4.32 has added support for an even finer-grained feature named now, which is a subset of the clock feature - that excludes timezone support, and so avoids pulling in many timezone related crates.

opentelemetry-stdout/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## vNext
 
+### Changed
+
+- Adjusted `chrono` features to reduce number of transitive dependencies. [#1569](https://github.com/open-telemetry/opentelemetry-rust/pull/1569)
+
 ## v0.2.0
 
 ### Changed

opentelemetry-stdout/Cargo.toml

@@ -22,7 +22,7 @@ logs = ["opentelemetry/logs", "opentelemetry_sdk/logs", "async-trait", "thiserro
 
 [dependencies]
 async-trait = { workspace = true, optional = true }
-chrono = { version = "0.4.22", default-features = false, features = ["clock"] }
+chrono = { version = "0.4.34", default-features = false, features = ["now"] }
 thiserror = { workspace = true, optional = true }
 futures-util = { workspace = true, optional = true }
 opentelemetry = { version = "0.21", path = "../opentelemetry", default_features = false }