Mention the Pass type as well in the changelog.

crucible-mir/CHANGELOG.md

@@ -3,6 +3,7 @@
 * The calling sequence of ```translateMIR``` has changed: the first argument,
   which should always have been passed as ```mempty```, has been removed.
   This will require adjustments in any downstream callers.
+* The corresponding implicit argument in the ```Pass``` type has been removed.
 * The Semigroup and Monoid instances for Collection, CollectionState, and
   RustModule have been removed. It is not expected that there are any
   downstream users.