Remove unused code notificationStyleChanged()

We may properly add it again later if necessary.

libraries/push/test/src/main/kotlin/io/element/android/libraries/push/test/FakePushService.kt

@@ -29,9 +29,6 @@ class FakePushService(
         Result.success(Unit)
     },
 ) : PushService {
-    override fun notificationStyleChanged() {
-    }
-
     override suspend fun getCurrentPushProvider(): PushProvider? {
         return availablePushProviders.firstOrNull()
     }