How can we use GitHub App Token instead of GITHUB_TOKEN

Hi All,
I have installed GitHub App successfully and now i would like to replace GITHUB_TOKEN with GitHub App token. but the problem is that GitHub App not generating token it only provide keys (private / secret with app id) so, is there any idea / suggestion for the following workflow.

          github_token: ${{ secrets.MERGEBOT_TOKEN }}  ---- **here i would like use GitHub App token** 
          reviewers: ${{ secrets.PLATFORM_REVIEWERS }}
          semver_match: minors
          MERGE_METHOD: rebase