mathlib3

1cb97275 - feat(field_theory/galois): Separable splitting field is Galois (#5347)

feat(field_theory/galois): Separable splitting field is Galois (#5347) Proves that a splitting field of a separable polynomial is Galois by showing that it has lots of automorphisms. Co-authored-by: tb65536 <tb65536@users.noreply.github.com>