mathlib3

0cc1fee5 - feat(linear_algebra/finsupp): lemmas for finsupp_tensor_finsupp (#6905)

feat(linear_algebra/finsupp): lemmas for finsupp_tensor_finsupp (#6905) Co-authored-by: Scott Morrison <scott.morrison@gmail.com> Co-authored-by: Eric Wieser <wieser.eric@gmail.com>