Fix "unused import" warning on Windows #338

Job	Run time
cargo fmt --all -- --check	6s
cargo check (ubuntu-latest)	8s
cargo test (ubuntu-latest)	45s
cargo check (macOS-latest)	12s
cargo test (macOS-latest)	3m 27s
cargo clippy -- -D warnings (ubuntu-latest)	8s
cargo check (windows-latest)	44s
cargo test (windows-latest)	4m 17s
cargo clippy -- -D warnings (macOS-latest)	12s
cargo clippy -- -D warnings (windows-latest)	1m 44s
Code Coverage (ubuntu-latest, unix)	2m 5s
GNU test suite	26s
Code Coverage (macos-latest, macos)	2m 35s
Code Coverage (windows-latest, windows)	6m 54s
	23m 43s

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