Types: Adjust type hints to incorporate None as the targets

[rabinadk1]

This pull request introduces changes to improve type annotations, enhance readability, and ensure consistency across multiple files in the pytorch_grad_cam library. The most important changes include updating function signatures to use Optional for nullable parameters, improving formatting for better readability, and refining type annotations for clarity.

Type Annotation Improvements:

• Updated function signatures across multiple files (pytorch_grad_cam/ablation_cam.py, pytorch_grad_cam/base_cam.py, pytorch_grad_cam/feature_factorization/deep_feature_factorization.py, pytorch_grad_cam/finer_cam.py, and pytorch_grad_cam/utils/image.py) to use Optional for nullable parameters, such as reshape_transform, targets, and concept_labels. [1] [2] [3] [4] [5] [6]

Code Formatting Enhancements:

• Reformatted function definitions to follow consistent indentation and improve readability, especially for functions with multiple parameters. This includes changes in __init__, forward, and other methods across several files. [1] [2] [3] [4]

Import Statement Refinements:

• Added Optional to relevant imports and removed unused modules like math and matplotlib in pytorch_grad_cam/utils/image.py. [1] [2] [3]

These changes collectively improve the maintainability and clarity of the codebase while ensuring type safety for nullable parameters.