Reduce JNI timeout duration from 40 to 20 seconds for improved responsiveness

lib/aniyomi_bridge.dart

@@ -320,7 +320,7 @@ class AniyomiBridge {
     _pendingRequests[message.id] = completer;
     _jniSenderPort.send(message);
     return completer.future.timeout(
-        const Duration(seconds: 40),
+        const Duration(seconds: 20),
         onTimeout: () => throw TimeoutException("JNI Isolate timed out")
     );
   }