CI improvement: check unused dependencies

[anaPerezGhiglia]

The goal is to have a CI job that validates that there aren'tt unused dependencies in the workspace.

Alternatives to consider

• cargo machete
  • https://github.com/bnjbvr/cargo-machete
  • might need to configure ignore rules prevent false positives
• cago udeps
  • https://github.com/est31/cargo-udeps
• cargo +nightly lint
  • https://doc.rust-lang.org/nightly/cargo/reference/lints.html#unused_dependencies
  • might produce false positives

Inspired by #1454