fix gcongr test

Author: YaelDillies

test/GCongr/inequalities.lean

@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Heather Macbeth
 -/
 import Mathlib.Algebra.BigOperators.Order
+import Mathlib.Algebra.Order.Field.Basic
 import Mathlib.Algebra.Parity
 import Mathlib.Tactic.Linarith
 import Mathlib.Tactic.GCongr