Support for dense Hessian and other improvements

Features

• dtypes are now inferred automatically instead of requiring to pass them manually #71
• n_output is also inferred #90
• adds support for Conv1d layers #76
• adds support for LayerNorm layers #80
• PVectors support pow #86
• KFAC and EKFAC support pow #87
• Support for dense Hessian matrices #91
• Support for binary classification FIMs #92
• PMat solve now supports working with PFMap objects (e.g. jacobians) #101
• Calculation of FIMs for multiclass classification is done using another formula, more numerically stable #102

Helpers:

• Gram matrix and Hessian helpers #97

Renaming (possibly breaking backward compatibility)

• Generators are renamed to Backends #96
• get_**** methods for obtaining dense pytorch versions of different objects are renamed to to_torch #100

CICD

• Updates to use uv, fixes PyPI and TestPyPI integration