mathlib3

44eb23a5 - chore(linear_algebra/matrix/adjugate): remove unnecessary fin_cases with (#16605)

chore(linear_algebra/matrix/adjugate): remove unnecessary fin_cases with (#16605) This was the only use of `fin_cases ... with ...` in mathlib, and it wasn't even necessary. Removing it to avoid having to port unused tactic features. Co-authored-by: Scott Morrison <scott.morrison@gmail.com>