Rust Cache warnings for tests with more than one feature enabled #43
Description
Looking at this CI log
Warning: ValidationError: Key Validation Error: v0-rust-1.56.1-i686-unknown-linux-gnu-alloc,simd--build_test-a732c1bed0bf174cd2e9b37132d29ed1815eb7cd-df69c652838aa8f1d3f759765b37bdf011baf599 cannot contain commas.
at checkKey (/home/runner/work/_actions/Swatinem/rust-cache/v2.0.0/dist/restore/index.js:58:15)
at Object.<anonymous> (/home/runner/work/_actions/Swatinem/rust-cache/v2.0.0/dist/restore/index.js:90:13)
at Generator.next (<anonymous>)
at /home/runner/work/_actions/Swatinem/rust-cache/v2.0.0/dist/restore/index.js:15:71
at new Promise (<anonymous>)
at __webpack_modules__.7799.__awaiter (/home/runner/work/_actions/Swatinem/rust-cache/v2.0.0/dist/restore/index.js:11:12)
at Object.restoreCache (/home/runner/work/_actions/Swatinem/rust-cache/v2.0.0/dist/restore/index.js:80:12)
at run (/home/runner/work/_actions/Swatinem/rust-cache/v2.0.0/dist/restore/index.js:62066:40)
it seems like Rust Cache does not like commas in keys.
This occurs because keys defined as
key: "${{ matrix.channel }}-${{ matrix.target }}-${{ matrix.features }}-${{ hashFiles('**/Cargo.lock') }}"
and they end up containing commas when ${{ matrix.features }} expands to two or more features, like "alloc,simd,simd-nightly".
Maybe the key definition should be changed to a comma-less verison. Also, a way to turn RustCache warnings into hard errors should be considered.