chore: update changelog

Author: vmphase

CHANGELOG.md

@@ -16,6 +16,9 @@ These changes are available on the `master` branch, but have not yet been releas
 
 ### Fixed
 
+- Fixed `RoleColours.is_holographic` raising `AttributeError` when `secondary` or
+  `tertiary` is `None`.
+  ([#3268](https://github.com/Pycord-Development/pycord/pull/3268))
 - Fix typehint for `SlashCommandGroup.__new__`.
   ([#3235](https://github.com/Pycord-Development/pycord/pull/3235))
 - Include `bypass_slowmode` in `Permissions.all`.