Add .tool-versions and .dvmrc support

[jessedijkstra]

Adds support for both .tool-versions and .dvmrc, implementation mirrors that of setup-node

[jessedijkstra]

@kt3k could you take a look at this? Currently required to use asdf in a repository that uses Deno but rather use the setup-deno action with .tool-versions.

[kt3k]

Thanks for your contribution!

Can you add test cases in .github/workflows/test.yml? Probably by adding something like the below (together with fixture .dvmrc and .tool-versions files) :

  # ...
  test-version-file:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        file: [".tool-versions", ".dvmrc"]
    steps:
      - uses: actions/checkout@v3

      - name: Setup Deno
        uses: ./
        with:
          deno-version-file: ${{ matrix.file }}

      - name: Check version
        run: deno -V | grep -q "deno 1\.43\.1"

[jessedijkstra]

@kt3k found a bug and fixed it by adding the tests, please take a look again when you have time.

[jessedijkstra]

Btw, based on the work of #54 :)

[kt3k]

LGTM. Thanks!