Fix PHP 8.1 Diffusion history errors
Summary:
Fix multiple PHP 8.1 errors when viewing Diffusion history.
Fixes T15573
Test Plan: View a diffusion history page. Eg https://my.php81.phorge.site/source/myrepo/history/master/
Reviewers: O1 Blessed Committers, speck
Reviewed By: O1 Blessed Committers, speck
Subscribers: speck, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Maniphest Tasks: T15573
Differential Revision: https://we.phorge.it/D25366