mathlib3

4a6b7168 - fix(tactic/nlinarith): stop nlinarith failing in the presence of squares when there is no order (#3417)

fix(tactic/nlinarith): stop nlinarith failing in the presence of squares when there is no order (#3417) As reported by Heather Macbeth at https://leanprover.zulipchat.com/#narrow/stream/113488-general/topic/app_builder_exception.20in.20.60nlinarith.60/near/204138256 Co-authored-by: Rob Lewis <rob.y.lewis@gmail.com>