Add cargo-deny and cargo-machete to CI

[erikjuhani]

Add cargo-deny (license and advisory checks) and cargo-machete (unused dependency detection) as steps in the test job in .github/workflows/test.yml.

- name: Deny
  run: cargo deny check

- name: Machete
  run: cargo machete

Both tools need to be installed via cargo install or a dedicated action before use.