fmt & clippy warns fixed #613

Job	Run time
Check cargo fmt	48s
cargo check	3m 37s
build with wasm-pack	3m 9s
cargo test (mac)	23m 13s
Verify MSRV	6m 19s
Verify Vendored Code	1m 12s
cargo test (win64)	17m 4s
cargo test doc (amd64)	22m 43s
Run sqllogictest with Postgres runner	3m 11s
check Cargo.toml formatting	1m 22s
clippy	4m 22s
check configs.md is up-to-date	2m 12s
cargo test hash collisions (amd64)	8m 28s
cargo doc	3m 11s
cargo test (amd64)	16m 5s
cargo test datafusion-cli (amd64)	2m 56s
cargo examples (amd64)	6m 44s
cargo test pyarrow (amd64)	4m 21s
verify benchmark results (amd64)	9m 58s
	2h 20m 55s

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