tidy clippy linting

[danieleades]

• add clippy config file aligned with MSRV set in CI
• move deny warnings from the CI script to a compiler flag to ensure consistent behaviour during development and CI
• address a few pedantic lints

[pksunkara]

We want the clippy to be run on stable, not msrv.

[danieleades]

We want the clippy to be run on stable, not msrv.

that's not what the clippy config does. setting the MSRV prevents clippy from suggesting changes that use syntax or features which are not compatible with the MSRV.

see https://github.com/rust-lang/rust-clippy#specifying-the-minimum-supported-rust-version

to add to that- if you use the msrv config option, there's no reason not to use nightly for clippy linting, rather than stable or MSRV

[pksunkara]

Thanks! ❤️