The link points to pages and pages of empty keys or obvious test keys, and this:

https://github.com/johndouthat/mydotfiles/blob/81b657398c71c...

A more useful link to have posted would have been eg: https://github.com/bobgilmore/githooks/blob/master/pre-commi...

... a pre-commit hook that prevents commits of private keys (among other things)

There doesn't seem to be any valid private key.

Check at the pages 11 and more