Fix be_within_spec

Author: toroidal-code

spec/matchers/be_within_spec.cpp

@@ -75,7 +75,7 @@ describe be_within_spec("expect(actual).to_be_within(delta).of(expected)", $  {
 
     it("fails when actual is outside the given percent variance", _ {
       auto base_formatter = Formatters::BaseFormatter();
-      auto ex = ExpectationValue(self, 20.1, std::source_location::current()).ignore();
+      auto ex = ExpectationValue(20.1, std::source_location::current());
       auto matcher = Matchers::BeWithinHelper(ex, 10).percent_of(10.0);
       expect(matcher.run()).to_fail_with("expected 20.1 to be within 10% of 10");
     });