chore: add more lints, fix some clippy warnings #903

Job	Run time
Build & test (stable, ubuntu-latest)	3m 11s
Build & test (stable, macos-latest)	2m 36s
Build & test (stable, windows-latest)	6m 33s
Build & test (nightly, ubuntu-latest)	2m 59s
Build & test (nightly, macos-latest)	3m 14s
Build & test (nightly, windows-latest)	6m 16s
Clippy lint checks	28s
Test coverage checks	3m 39s
Test with external dependencies	1m 59s
Build with each feature combination	19s
Machete dependencies checks	7s
Miri test	7m 50s
Minimal dependency versions build	52s
Code formatting checks	22s
	40m 25s

Provide feedback