chore(topology/sheaves): speed up a slow proof (#6879)
chore(topology/sheaves): speed up a slow proof (#6879)

In another branch this proof mysteriously becomes slightly too slow, so I'm offering a pre-emptive speed up, just replacing `simp` with `rw`.



Co-authored-by: Scott Morrison <63f04b4d96235eb042cc46d94f14d241d2a26722@gmail.com>

leanprover-community/mathlib,leanprover-community/mathlib