mathlib3

5d0a40f1 - feat(algebra/algebra/{basic,tower}): add alg_equiv.comap and alg_equiv.restrict_scalars (#6548)

feat(algebra/algebra/{basic,tower}): add alg_equiv.comap and alg_equiv.restrict_scalars (#6548) This also renames `is_scalar_tower.restrict_base` to `alg_hom.restrict_scalars`, to enable dot notation and match `linear_map.restrict_scalars`.