A line ending invariant alternative to hashFiles

Describe the enhancement
Sometimes cached data is sufficiently cross-platform to be reused across runners on Windows and the Unix OSes. A problem arises if the cache key needs to be computed by hash-summing text files, which produces differing hash sums on the same file if it was e.g. checked out by git in text mode applying auto-conversion to the line endings.

This workflow run failed to hit the cache in the Windows test job, even though the preceding update-deps job on Linux had stored it.

Code Snippet
It would be nice if a hashTextFiles function was available that would canonicalize line endings for the hash input:

  test:
    needs: update-deps
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
    runs-on: ${{ matrix.os }}
    steps:
      - uses: actions/checkout@v2
      - id: cargo-registry
        name: Restore cargo registry
        uses: actions/cache@v1
        with:
          path: ~/.cargo/registry
          key: cargo-registry-${{ hashTextFiles('**/Cargo.lock') }}

The issue points to a proposed hashTextFiles expression in the workflow example, with Cargo.lock as the input, and references actions/checkout@v2 and actions/cache@v1. Start by tracing the existing hashFiles behavior; done means equivalent text files produce the same cache key across the Linux, Windows, and macOS jobs.