ci: cache dependencies

[xtqqczze]

For example cargo-audit could be installed before setting up the cache:

string-interner/.github/workflows/rust.yml

Lines 124 to 127 in a8be633

	- name: Set up Rust cache
	uses: Swatinem/rust-cache@v2
	- name: Install `cargo-audit`
	run: cargo install cargo-audit