Updated base_model.py to account for importing error

[Himanshu-Verma-ds]

changed the importing of pytorch-forecasting in order to account for this error "model must be a LightningModule or torch._dynamo.OptimizedModule, got TemporalFusionTransformer"

Description

This PR solves the issue of importing of pytorch-forecasting in order to account for this error "model must be a LightningModule or torch._dynamo.OptimizedModule, got TemporalFusionTransformer"

Checklist

• Linked issues (if existing)
• Amended changelog for large changes (and added myself there as contributor)
• Added/modified tests
• Used pre-commit hooks when committing to ensure that code is compliant with hooks. Install hooks with pre-commit install.
  To run hooks independent of commit, execute pre-commit run --all-files

Make sure to have fun coding!