Add `tracing` feature (#6) #43

Job	Run time
Lint	32s
Test Rust source (stable, ubuntu-latest)	13s
Test Rust source (stable, windows-latest)	1m 37s
Test Rust source (stable, macos-latest)	17s
Test Rust source (nightly, ubuntu-latest)	14s
Test Rust source (nightly, windows-latest)	1m 5s
Test Rust source (nightly, macos-latest)	17s
Test crate release	8s
Release crate	0s
	4m 23s

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