title: How to get github app installation id on pull request event?
body: <p>I am creating a build pipeline with Github which will be create a check-run on every pull-request to analyse the performance of my application. I have created and installed the Github app to my repo and generated the private key. I need to perform <code>Authenticating as an installation</code> to get an access-token. </p>
  
  <p><a href="https://developer.github.com/apps/building-github-apps/authenticating-with-github-apps/#authenticating-as-a-github-app" rel="nofollow noreferrer">But as per the docs</a> to get an access-token for installation, first i have to get list of installations of that app and have to find the specific installation from that list. But i am clueless how to identify the specific installation_id of app for pull request event raised on particular repository that installed my app.</p>
  
  <p>I don't know what i am missing.</p>