android: add note about required Gadgetbridge version to ChangeLog

Author: thyttan

apps/android/ChangeLog

@@ -43,5 +43,6 @@
 0.40: Ensure we send health 'activity' message to gadgetbridge (added 2v26)
 0.41: When using `actfetch`, fetch historical activity type too
 0.42: Add handling for android STREAM_MUSIC volume level info, emitting on
-      arrival.
+      arrival. (Needs Gadgetbridge nightly (either flavor) for now, or stable
+      version 85 when it's out)