Fix dark mode support for Changelog
Fix dark mode support for Changelog

Summary:
Fix changelog display in dark mode, as reported in https://github.com/facebook/flipper/issues/2379#issuecomment-851059786

Changelog: Fix dark mode support in changelog dialog.

Reviewed By: timur-valiev

Differential Revision: D29801181

fbshipit-source-id: ffbbd012c99dee897c4fd67653b4f6375294d668

facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper