Minor cleanup

- Add pending intent immutable flags to satisfy lint warnings
- Change AddDuplicateMangaDialog arg to a function instead to avoid leaking controller-specific logic into it
- Require WebView 99+

app/src/main/java/eu/kanade/tachiyomi/data/library/LibraryUpdateNotifier.kt

@@ -339,7 +339,7 @@ class LibraryUpdateNotifier(private val context: Context) {
             flags = Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_SINGLE_TOP
             action = MainActivity.SHORTCUT_RECENTLY_UPDATED
         }
-        return PendingIntent.getActivity(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)
+        return PendingIntent.getActivity(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE)
     }
 
     companion object {