Forked repos fork link getting removed by the safe-settings

## Problem Description
Hi @decyjphr
I have created my own instances of safe-settings app since we are working in a pvt org.We have used the azure function deployment strategy to create our own probot app and have integrated your code in our codebase.Things are working fine but we found a bug when we have forked a repo in an org where the safe-settings is being installed then the repo settings are getting updated and along with that the forking link is also getting disappered.At the end it displays that the repo is newly created and not forked.
I would like to know is it what expected or forked repos case is not being handled by safe-settings
### What is the expected behavior
I think we should update the repo settings as per the given settings in .yml file but the forking link and all should not be removed.

## Context

### Are you using the hosted instance of probot/settings or running your own?
running on our own
### If running your own instance, are you using it with github.com or GitHub Enterprise?
GitHub Enterprise
#### Version of probot/settings
12.2.8
#### Version of GitHub Enterprise
3.6