Add context output after run

PR for #20 issue

Add outputs context like version-check repo.

Outputs

changed: either "true" or "false", indicates whether the version has changed.
version: if the version has changed, it shows the version number (e.g. "1.0.2")
commit: if the version has changed, it shows the sha of the commit where the change has been found.

To access these outputs, you need to access the context of the step you previously set up: you can find more info about steps contexts here.
If you set your step id to check you'll find the outputs at steps.check.outputs.OUTPUT_NAME: you can use these outputs as conditions for other steps.
Here's an example:

- name: Publish if version has been updated
  id: check
  uses: pascalgn/npm-publish-action@f6302932be3d13d292168d31a9ea193c717567ff
              # This is tagged version v1.3.7, but do not use version tags
              # https://julienrenaux.fr/2019/12/20/github-actions-security-risk/

- name: Log when changed
  if: steps.check.outputs.changed == 'true'
  run: 'echo "Version change found in commit ${{ steps.check.outputs.commit }}! New version: ${{ steps.check.outputs.version }}"'

- name: Log when unchanged
  if: steps.check.outputs.changed == 'false'
  run: 'echo "No version change :/"'

pascalgn / npm-publish-action

Add context output after run #37

Outputs