chore: clippy fixes #999

Job	Run time
Code coverage	3m 31s
Clippy (main package)	17s
Check	13s
Clippy (all code)	1m 5s
Documentation	11s
Rustfmt	5s
Check with minimal Rust version	45s
Mutation tests (0)	2m 21s
Mutation tests (1)	2m 20s
Test all features	39s
Mutation tests (2)	2m 21s
Test feature alpha-async-tokio-rusqlite	35s
Mutation tests (3)	2m 19s
Test examples	34s
Test feature from-directory	34s
Test no features	34s
	18m 24s

Provide feedback