Updated PyG graph classification colab to make WandB optional

[soumik12345]

Note: WandB usage is only made optional for experiment tracking during training and not during EDA, which is dependent on WandB functionalities.

[review-notebook-app[bot]]

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[github-actions[bot]]

The following colabs where changed -colabs/pyg/Graph_Classification_with_PyG_and_W&B.ipynb

[soumik12345]

@morganmcg1 Usage of WandB is now completely optional.