lrp missing rules fixed

[kamilrzechowski]

Description

The PR adds missing rules for the LRP explainer, according to the paper.

Some rules for Sigmoid, HardSwish, and Flatten are missing in the LRP captum explainer. The given PR adds gamma rules for initial model layers, epsilon to final model layers, and epsilon=0 rule to the last layer.

Checklist:

• I have updated all related pyproject.toml files.
• I have updated lock files.
• I have set an Assignee and Reviewers.
• I have labeled the PR correctly.
• I have performed a self-review of my own code.
• I have covered my code and changes with unit tests.
• I have annotated types as extensively as possible.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• All code references and dependencies will work.

[adamwawrzynski]

LGTM