Fix the linting job

[richardpringle]

The linter just fails with clippy and fmt not installed, but then shows up as passing.

It would be much better if the commands were specified directly in the jobs and if they were made simpler.

For instance, we should only be running cargo clippy --all --all-features --examples --tests -- -Dwarnings. If anyone wants to see what's failing, it's easy for them to checkout the .github directory and see the commands all in one place without being lead to separate files.

And, in order to check specific rules, those rules can be specified in lib.rs for each individual crate. For example, just place !#[deny(clippy::pedantic)] at the top of lib.rs instead of calling cargo clippy -- -D clippy::pedantic