Remove hardcoded dithering value in NeMo transducer recognizer (#2639)

Author: vsd-vector

sherpa-onnx/csrc/offline-recognizer-transducer-nemo-impl.h

@@ -147,8 +147,6 @@ class OfflineRecognizerTransducerNeMoImpl : public OfflineRecognizerImpl {
     config_.feat_config.nemo_normalize_type =
         model_->FeatureNormalizationMethod();
 
-    config_.feat_config.dither = 0;
-
     if (model_->IsGigaAM()) {
       config_.feat_config.low_freq = 0;
       config_.feat_config.high_freq = 8000;