Add cargo data caching to CI workflow #5

	name: CI
	on:
	push:
	paths:
	- .github/workflows/ci.yaml
	- 'firmware/**'
	pull_request:
	paths:
	- .github/workflows/ci.yaml
	- 'firmware/**'

	env:
	CARGO_TERM_COLOR: always
	defaults:
	run:
	working-directory: firmware

	jobs:
	check:
	name: Check
	runs-on: ubuntu-latest
	steps:
	- name: Install Rust
	uses: dtolnay/rust-toolchain@stable
	with:
	targets: riscv32imc-unknown-none-elf
	components: clippy, rust-src, rustfmt
	- name: Check out repository
	uses: actions/checkout@v4
	- name: Cache cargo data
	uses: actions/cache@v4
	with:
	path: \|
	~/.cargo/git
	~/.cargo/registry
	# intentionally not caching `target/` here yet
	key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
	- name: Check formatting
	run: cargo fmt --all --check
	- name: Clippy
	run: cargo clippy --workspace --all-targets --all-features -- --deny warnings --allow deprecated

	build:
	name: Build
	needs: [check]
	runs-on: ubuntu-latest
	steps:
	- name: Install Rust
	uses: dtolnay/rust-toolchain@stable
	with:
	targets: riscv32imc-unknown-none-elf
	- name: Check out repository
	uses: actions/checkout@v4
	- name: Cache cargo data
	uses: actions/cache@v4
	with:
	path: \|
	~/.cargo/git
	~/.cargo/registry
	# intentionally not caching `target/` here yet
	key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
	- name: Build everything
	run: cargo build --workspace --all-targets --release

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