Unbalanced low-rank Gromov-Wasserstein

What's Changed

• introduce new norm operator that can differentiate through lambda x: norm(x-x) + lighter tests across the board by @marcocuturi in #411
• Feature/better io callbacks by @michalk8 in #413
• Feature/optional dependencies by @michalk8 in #412
• Update pre-commits by @michalk8 in #416
• Feature/move solve by @michalk8 in #418
• Feature/lineax ridge by @michalk8 in #424
• Feature/ulrgw by @michalk8 in #410

Full Changelog: 0.4.3...0.4.4