Minor fix in model_predict.py

[ltorada]

Parenthesis missing in selene/selene_sdk/predict/model_predict.py, line 463:

(batch_ids and i == 0) or i % self.batch_size != 0)

[kathyxchen]

@ltorada thanks very much - you are welcome to submit a pull request with this update, or I'll push a fix shortly