The app_id attribute in required_status_checks.checks is a rather difficult parameter to retrieve.

As pointed out by @netomi in #64 (comment) using the application slug would be easier. Application slugs:

• Correspond, as far as I understand to the last URL component in https://github.com/marketplace/.
• For internal GitHub apps that are not listed in the marketplace, the slug can be verified at https://github.com/apps/<app_slug>.
• Can be converted into an id through the https://api.github.com/apps/<app_slug> REST endpoint.

I can submit a PR for this feature request.