* gradual da

* gradual da

* implement gradual domain adaptation

* fix docstring

* fix docstrings

* add more comprehensive tests

* Improves clarity of variable names (`X_t` -> `X_step`), and improves testing of estimator-fit condition

---------

Co-authored-by: Julie Alberge <julie.alberge@gmail.com>
Co-authored-by: Théo Gnassounou <66993815+tgnassou@users.noreply.github.com>

Bumps the actions group with 1 update: [actions/checkout](https://github.com/actions/checkout).


Updates `actions/checkout` from 5 to 6
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* start fixing problem

* continue fixing

* continue fixing

* fix scorer

* fix spherical kmeans

* add the hook class to be pickable

* fix torch import

* add the hook class to be pickable

* use cross_validate instead of cross_val_score

* add name of parameters

* fix scorer functions

* fix last test

* specify the parameters sample domain in deep scorer test

* remove comments

* MAINT fix metadata licence

* remove metadata from classifier

---------

Co-authored-by: Théo Gnassounou <66993815+tgnassou@users.noreply.github.com>

Bumps the actions group with 1 update: [actions/cache](https://github.com/actions/cache).


Updates `actions/cache` from 4 to 5
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v4...v5)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Théo Gnassounou <66993815+tgnassou@users.noreply.github.com>

Co-authored-by: Rémi Flamary <remi.flamary@gmail.com>
Co-authored-by: Théo Gnassounou <66993815+tgnassou@users.noreply.github.com>