Fix another hanging bug in text classifiction model.
This pull request **introduces 2 alerts** when merging 260e83eac7de1938e07b5665c52b5d5f26906d50 into 536cf58e010a5ce389ed16ce52acce80e5524a1d - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-7330a0019def9291ed2c5484a46b6fc4616b32f2)

**new alerts:**

* 2 for Unused import