GitHub Action - Invalid workflow file - YAML syntax error

I am trying to setup my first GitHub Workflow and I am facing many YAML syntax issues even I am using the official documentation.

I am using the below YAML:

# This is a basic workflow to help you get started with Actions

name: TestWorkflowGithub

# Controls when the workflow will run
on:
  # Triggers the workflow on push or pull request events but only for the "main" branch
  pull_request:
    branches:
    - 'testbranch/**'
# A workflow run is made up of one or more jobs that can run sequentially or in parallel
jobs:
  # The type of runner that the job will run on
  runs-on: ubuntu-latest

  # Steps represent a sequence of tasks that will be executed as part of the job
  steps:
    - name: Checkout the code
      uses: actions/checkout@v3

    - name: Install PMD
      run: |
        PMD_VERSION=`cat pmd/pmd-version.txt`
        wget https://github.com/pmd/pmd/releases/download/pmd_releases%2F6.54.0/pmd-bin-6.54.0.zip
        unzip pmd-bin-6.54.0.zip -d ~
        mv ~/pmd-bin-$6.54.0 ~/pmd
        ~/pmd/bin/run.sh pmd --version

    # Run PMD scandd
    - name: Run PMD scan
      run: ~/pmd/bin/run.sh pmd -d force-app -R pmd/ruleset.xml -f text

GitHub is showing me the below error:
You have an error in your yaml syntax on line 14

Note: the line 14 is "runs-on: ubuntu-latest"

Which is the syntax issue in the above YAML file?

You are missing the job identifier:

jobs:
  foo: # <-- This
    runs-on: ubuntu-latest

    steps:
      - name: Checkout the code
        uses: actions/checkout@v3

  steps:

You can use actionlint or vscode-yaml to avoid such syntax issues next time

A good way to quickly pinpoint the syntax issue in your YAML file is to use the new VSCode extension:

> ## GitHub Actions: Visual Studio Code Extension is now in public beta (Mar. 2023)
>
> The GitHub Actions extension for VS Code is now in public beta.
> This extension includes rich editing features, such as syntax validation and autocomplete, making workflow authoring and editing faster and easier.
> Developers will also be able to view workflow runs, inspect logs, and trigger re-runs directly from VS Code.
>
> To get started, visit the VS Code Marketplace or learn more about the extension's capabilities from the Actions VS Code Extension blog post.
>
> See what's next for Actions by visiting our public roadmap.