add unused import #62

Job	Run time
cargo check	10m 47s
build with wasm-pack	2m 45s
cargo test (macos)	15m 44s
cargo test (macos-aarch64)	11m 20s
cargo test (win64)	44m 33s
Verify Vendored Code	39s
Check cargo fmt	30s
Verify MSRV (Min Supported Rust Version)	7m 9s
cargo test (amd64)	10m 2s
check configs.md is up-to-date	3m 0s
clippy	2m 14s
check Cargo.toml formatting	3m 5s
cargo test hash collisions (amd64)	14m 49s
cargo doc	4m 0s
cargo test datafusion-cli (amd64)	3m 52s
cargo test doc (amd64)	15m 29s
Run sqllogictest with Postgres runner	3m 35s
cargo test pyarrow (amd64)	2m 50s
cargo examples (amd64)	14m 7s
verify benchmark results (amd64)	12m 34s
	3h 3m 4s

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