feature: Add {old_pull_request_body} and {old_pull_request_title}

[hwhsu1231]

Feature Request

Hello, Maintainance Team.

I hope that github-cherry-pick-action can provide the following two special variables:

1. {old_pull_request_body}
2. {old_pull_request_title} (same as the {old_title})

Because I would like to apply this GitHub Action in the following form:

      - name: Cherry Pick into 'source/git-master' branch
        uses: carloscastrojumo/github-cherry-pick-action@v1.0.10
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          branch: 'source/git-master'
          labels: 'cherry-pick, automerge'
          force: true
          title: |
            {old_pull_request_title}
          body: |
            {old_pull_request_body}

            Cherry-picked from #{old_pull_request_id}

Therefore, I would need a special variable to reference the body of the old pull request, {old_pull_request_body}.

As for {old_pull_request_title}, it's simply to make the naming more systematic.

Version

• github-cherry-pick-action: v1.0.10