Add pull request title to end of changelog file on PR merge

changelog.yml

on:
  pull_request:
    branches:
      - dev
    types: [closed]

jobs:
  update_changelog:
    name: Update and Commit Changelog
    runs-on: ubuntu-latest
    if: github.event.pull_request.merged == true
    steps:
      # Checkout git.
      - uses: actions/checkout@v2
        with:
          ref: dev # checkout dev branch.
          fetch-depth: 0 # fetch all history.

      - run: git config --global user.email "[email protected]"
      - run: git config --global user.name "SomeUsername"

      - name: Create Changelog Entry String
        run: |
          cl_entry="${{ github.event.pull_request.title }}  "
          cl_entry="${cl_entry//'%'/'%25'}"
          cl_entry="${cl_entry//$'\n'/'%0A'}"
          cl_entry="${cl_entry//$'\r'/'%0D'}"
          echo "::set-output name=content::$cl_entry"
        id: changelog

      # Update changelog.
      - run: |
          echo "${{ steps.changelog.outputs.content }}" >> changelog-dev.md

      # Commit changes.
      - run: git add changelog-dev.md
      - run: git commit -m "Update Changelog" || echo "No changes to commit"
      - run: git push origin dev