refactor(ring_theory/algebra): alg_hom extends ring_hom and use curly brackets (#1529)
* chore(algebra/ring): use curly brackets for ring_hom where possible
* refactor(ring_theory/algebra): alg_hom extends ring_hom and use curly brackets
* fix build
* Update src/ring_theory/algebra.lean
Co-Authored-By: Johan Commelin <johan@commelin.net>
* fix build