Fix typo in changelog for v8.0.0

[HonkingGoose]

There's a typo in the changelog for v8.0.0:

New option labels-to-remove-when-stale enables users to specify list of coma delimited labels that will be removed when the issue or PR becomes stale by @panticmilos #770

The word coma should be changed to comma.

[MaksimZhukov]

Hello @HonkingGoose !
Thank you for noticing this! Fixed

[HonkingGoose]

Thank you for fixing it! ❤️