GPU memory is used although cpu() is called
I run the following commands: 

```
import nemo
import nemo.collections.asr as nemo_asr
import nemo.collections.nlp as nemo_nlp
import nemo.collections.tts as nemo_tts

quartznet = nemo_asr.models.EncDecCTCModel.from_pretrained(model_name="stt_en_quartznet15x5").cpu()
English_text = quartznet.transcribe(['~/audio1.wav'])

```

In the output of `nvidia-smi`, I see that `800 Mb` of GPU is used when running the above commands. Why? My expectation is that no GPU memory should be used when I use `cpu()`. 

