add unused import #63

Job	Run time
Check cargo fmt	34s
cargo check	10m 32s
build with wasm-pack	2m 38s
cargo test (macos)	10m 27s
cargo test (macos-aarch64)	11m 1s
cargo test (win64)	48m 41s
Verify Vendored Code	39s
Verify MSRV (Min Supported Rust Version)	7m 3s
cargo test datafusion-cli (amd64)	3m 53s
cargo doc	3m 50s
clippy	2m 21s
cargo test (amd64)	10m 8s
cargo test doc (amd64)	15m 17s
Run sqllogictest with Postgres runner	3m 34s
cargo examples (amd64)	13m 39s
cargo test pyarrow (amd64)	2m 55s
verify benchmark results (amd64)	12m 20s
check Cargo.toml formatting	2m 56s
check configs.md is up-to-date	2m 37s
cargo test hash collisions (amd64)	14m 35s
	2h 59m 40s

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