Asses the impact of deprecated GitHub webhook API

[jleach]

GitHub is deprecating some web hooks that the but is using. Lets asses the impact on the bot and/or probot framework.

Hi @bcgov Admin,

We're contacting you regarding upcoming changes to GitHub Apps owned by your organization:
 - Repo Mountie

We no longer support two events which your GitHub Apps may rely on, "integration_installation" and "integration_installation_repositories".

These events can be replaced with the "installation" and "installation_repositories" events respectively. 

The "integration_installation" and "integration_installation_repositories" events will be removed after October 1st, 2020.

Please visit https://developer.github.com/changes/2020-04-15-replacing-the-installation-and-installation-repositories-events for more information about suggested changes, brownouts, and removal dates.

Thanks,
The GitHub Team