Support .dvmrc

[BrunoBernardino]

I personally use a .dvmrc file to keep track of the deno version used for that specific repo/project, so it would be helpful to have the possibility to have the action read that instead of having to update in two places.

This is supported by actions/setup-node, like:

  - name: Setup node
    uses: actions/setup-node@v2
    with:
      node-version-file: '.nvmrc'

So it could be supported with something like:

  - name: Setup Deno
    uses: denoland/setup-deno@v1
    with:
      deno-version-file: '.dvmrc'

[lishaduck]

Supported since 1.2.0.