mathlib3

05e1845c - feat(archive/100-theorems-list): add proof of the solution of the cubic (#11635)

feat(archive/100-theorems-list): add proof of the solution of the cubic (#11635) Gives solution to the cubic equation, based on the cardano's formula. The base field should have cube root of unity and characteristic neither 2 nor 3. Co-authored-by: Kyle Miller <kmill31415@gmail.com>