[Feature Request] Use GITHUB_TOKEN as default

[qoomon]

Would be nice if this action would make use of default inputs to pass github token to keep this action as lean as possible. action.yaml

inputs: 
  token:
    description: 'A GitHub access token'
    required: true
    default: ${{ github.token }}

[chenrui333]

@qoomon sounds good to me, feel free to drop a PR.