Update Real.lean

Author: CoolRmal

Mathlib/MeasureTheory/Integral/RieszMarkovKakutani/Real.lean

@@ -399,7 +399,7 @@ then they are equal. -/
 theorem _root_.MeasureTheory.Measure.ext_of_integral_eq_on_compactlySupported
     [μ.Regular] [ν.Regular] (hμν : ∀ f : C_c(X, ℝ), ∫ x, f x ∂μ = ∫ x, f x ∂ν) :
     μ = ν := by
-  apply Measure.OuterRegular.eq_of_eq_on_isOpen
+  apply Measure.OuterRegular.ext_isOpen
   apply Measure.InnerRegularWRT.eq_on_outer_of_eq_on_inner Measure.Regular.innerRegular
     Measure.Regular.innerRegular
   intro K hK