fix predicate validator test

Author: pnilan

unit_tests/sources/declarative/validators/test_predicate_validator.py

@@ -40,7 +40,7 @@ def test_given_invalid_input_when_validate_then_raise_value_error(self):
         with pytest.raises(ValueError) as context:
             validator.validate()
 
-        assert error_message in str(context.exception)
+        assert error_message in str(context.value)
         assert strategy.validate_called
         assert strategy.validated_value == test_value