mathlib3

5228d557 - feat(linear_algebra/basic): add span_zero (#3306)

feat(linear_algebra/basic): add span_zero (#3306) `simp` now proves span_zero for both submodules and ideals Co-authored-by: Rob Lewis <Rob.y.lewis@gmail.com> Co-authored-by: Bryan Gin-ge Chen <bryangingechen@gmail.com>