I am trying to setup a github action but I have an invalid yaml syntax on line 20 run: echo "Merged PR detected: ${{ github.event.pull_request.head.ref }}":

name: Auto Delete Feature Branch

on:
  pull_request:
    types: [closed]
    branches:
      - develop
  push:
    branches:
      - develop

jobs:
  delete-branch:
    runs-on: ubuntu-latest

    steps:
    - name: Check if it's a merged PR
      if: github.event.pull_request.merged == true
      id: check_merge
      run: echo "Merged PR detected: ${{ github.event.pull_request.head.ref }}"

    - name: Set branch name from merged PR
      if: github.event.pull_request.merged == true
      id: set_branch_name_from_pr
      run: echo "::set-output name=BRANCH_NAME::${{ github.event.pull_request.head.ref }}"

    - name: Set branch name from commit message
      if: github.event.pull_request.merged != true
      id: set_branch_name_from_commit
      run: |
        COMMIT_MESSAGE=$(git log -1 --pretty=%B)
        if [[ "$COMMIT_MESSAGE" =~ Merge branch 'feature/([^']+)' ]]; then
          echo "::set-output name=BRANCH_NAME::feature/${BASH_REMATCH[1]}"
        else
          echo "::set-output name=BRANCH_NAME::"
        fi
    - name: Delete feature branch
      if: steps.set_branch_name_from_pr.outputs.BRANCH_NAME != '' || steps.set_branch_name_from_commit.outputs.BRANCH_NAME != ''
      env:
        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      run: |
        BRANCH_NAME=${{ steps.set_branch_name_from_pr.outputs.BRANCH_NAME || steps.set_branch_name_from_commit.outputs.BRANCH_NAME }}
        if [[ $BRANCH_NAME == feature/* ]]; then
          git push origin --delete $BRANCH_NAME
        else
          echo "No feature branch to delete"
        fi

I am quite new to yaml so I don’t know what is wrong with this syntax. I tried using a linter on the internet and it says Nested mappings are not allowed in compact mappings at line 20, column 12 but I could not find what it means.