bors already tests the *result* of merging PRs into master, and then
pushes the *exact same commit* to master on success, so it's guaranteed
to pass CI. No point in running everything again.
This'll make other CI runs faster, since we have so many jobs that we're
always running against the GHA limit of 10 concurrent jobs.
It can be rather surprising when new lints pop up when a new stable
toolchain is released. Let's pin this check to a specific version to
avoid those surprises.
Might as well run the lints on our tests and examples. When I first
started doing this cleanup, I thought this was the default, but I must
have run `cargo clippy --all-targets` at some point in there.
Dario Nieuwenhuis
Thibaut Vandervelden
Alex Crawford
Adam Greig