Running Token_Classification-BioMegatron notebook in colab, failed with apex error
**Describe the bug**
01. Running this notebook in colab: 
https://github.com/NVIDIA/NeMo/blob/main/tutorials/nlp/Token_Classification-BioMegatron.ipynb

02. encountered apex error. Follow the steps in readme file to install apex, successful.
Additional context:
user = False
home = None
root = None
prefix = None
Successfully installed apex-0.1
Removed build tracker: '/tmp/pip-req-tracker-k560_7qd'

03. continue running the codes and it fail at model training
import apex (this line no error)
model_ner = nemo_nlp.models.TokenClassificationModel(cfg=config.model, trainer=trainer)

error:
[NeMo W 2022-11-02 09:07:02 lm_utils:81] biomegatron345m_biovocab_30k_cased is not in get_pretrained_lm_models_list(include_external=False), will be using AutoModel from HuggingFace.
[NeMo I 2022-11-02 09:07:02 cloud:56] Found existing object /root/.cache/torch/NeMo/NeMo_1.13.0rc0/BioMegatron345m-biovocab-30k-cased/5885010653185bba59bf489ff757bf09/BioMegatron345m-biovocab-30k-cased.nemo.
[NeMo I 2022-11-02 09:07:02 cloud:62] Re-using file from: /root/.cache/torch/NeMo/NeMo_1.13.0rc0/BioMegatron345m-biovocab-30k-cased/5885010653185bba59bf489ff757bf09/BioMegatron345m-biovocab-30k-cased.nemo
[NeMo I 2022-11-02 09:07:02 common:911] Instantiating model from pre-trained checkpoint
[NeMo E 2022-11-02 09:07:07 common:504] Model instantiation failed!
    Target class:	nemo.collections.nlp.models.language_modeling.megatron_bert_model.MegatronBertModel
    Error(s):	Apex was not found. Please see the NeMo README for installation instructions: https://github.com/NVIDIA/NeMo#megatron-gpt.
    Traceback (most recent call last):
      File "/usr/local/lib/python3.7/dist-packages/nemo/core/classes/common.py", line 483, in from_config_dict
        instance = imported_cls(cfg=config, trainer=trainer)
      File "/usr/local/lib/python3.7/dist-packages/nemo/collections/nlp/models/language_modeling/megatron_bert_model.py", line 56, in __init__
        "Apex was not found. Please see the NeMo README for installation instructions: https://github.com/NVIDIA/NeMo#megatron-gpt."
    ImportError: Apex was not found. Please see the NeMo README for installation instructions: https://github.com/NVIDIA/NeMo#megatron-gpt.
    
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
[<ipython-input-29-1f0d02a2ff61>](https://localhost:8080/#) in <module>
----> 1 model_ner = nemo_nlp.models.TokenClassificationModel(cfg=config.model, trainer=trainer)
      2 
      3 #ImportError: Apex was not found. Please see the NeMo README for installation instructions: https://github.com/NVIDIA/NeMo#megatron-gpt.
      4 #Successfully installed apex-0.1

9 frames
[/usr/local/lib/python3.7/dist-packages/nemo/collections/nlp/models/language_modeling/megatron_bert_model.py](https://localhost:8080/#) in __init__(self, cfg, trainer)
     54         if not HAVE_APEX:
     55             raise ImportError(
---> 56                 "Apex was not found. Please see the NeMo README for installation instructions: https://github.com/NVIDIA/NeMo#megatron-gpt."
     57             )
     58         super().__init__(cfg, trainer=trainer, no_lm_init=False)

ImportError: Apex was not found. Please see the NeMo README for installation instructions: https://github.com/NVIDIA/NeMo#megatron-gpt.

**Expected behavior**
Model training should be successful.


**Environment overview (please complete the following information)**
running tutorial notebook in colab.

