Support quoted actions

[jaimergp]

Noticed gha-update chokes on this type of input (note quoted uses value):

      - id: 'auth'
        name: 'Authenticate to Google Cloud'
        uses: 'google-github-actions/auth@v0'
        with:
          credentials_json: ${{ secrets.GOOGLE_CREDENTIALS }}

[davidism]

Nice! I intended to fix this with a broader refactor, but I ran out of time. Thanks.

[jaimergp]

@davidism sorry I forgot about this, I now applied your suggestion. Thanks!