Using clippy as a library has been deprecated, instead the `cargo
clippy` command should be used instead. To comply with this change
clippy has been removed from the `Cargo.toml` and is now installed with
cargo when building in CI.
This has also lead to a few new clippy issues to show up, this includes
everything in the `font` subdirectory. This has been fixed and `font`
should now be covered by clippy CI too.
This also upgrades all dependencies, as a result this fixes#1341 and
this fixes#1344.