Auto merge dependabot PR after all checks have passed

I want to auto-merge Dependabot PR once all checks(or workflows) on Dependabot PR have been passed.

Currently, I am using this logic to trigger auto-merge action:

on:
  workflow_run:
    workflows: ["Lint and Unit tests"]
    types:
      - completed

Once all checks are passed on the Dependabot PR it triggers the auto-merge workflow but the issue is that it does not work due to a lack of pull_request payload in the workflow.

Errors and warnings on auto-merge workflow:

Following workflow does it for us:

name: Dependabot auto-merge
on:
  pull_request_target:
    types: [review_requested]

permissions:
  contents: write
  pull-requests: write
  packages: read

jobs:
  dependabot:
    runs-on: ubuntu-latest
    if: ${{ github.actor == 'dependabot[bot]' }}
    steps:
      - name: Dependabot metadata
        id: metadata
        uses: dependabot/fetch-metadata@v1.3.4
        with:
          github-token: "${{ secrets.GITHUB_TOKEN }}"
          skip-commit-verification: true

      - name: Checkout repository
        uses: actions/checkout@v3

      - name: Approve a PR if not already approved
        run: |
          gh pr checkout "$PR_URL"
            if [ "$(gh pr status --json reviewDecision -q .currentBranch.reviewDecision)" != "APPROVED" ];
          then
            gh pr review --approve "$PR_URL"
          else
            echo "PR already approved.";
          fi
        env:
          PR_URL: ${{github.event.pull_request.html_url}}
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}

      - name: Enable auto-merge for Dependabot PRs
        if: ${{ contains(github.event.pull_request.title, 'bump')}}
        run: gh pr merge --auto --merge "$PR_URL"
        env:
          PR_URL: ${{github.event.pull_request.html_url}}
          GITHUB_TOKEN: ${{secrets.RELEASE_TOKEN}}

Where RELEASE_TOKEN has extended scopes (workflow, write:packages, admin:org), branch protection is activated (review is required), dependabot is configured to have 'reviewers:' set, auto merge is enabled at org and repo level.