test: deactivate error check for hetero array

if TOML11_USE_UNRELEASED_TOML_FEATURES is activated.

tests/test_error_detection.cpp

@@ -80,10 +80,14 @@ BOOST_AUTO_TEST_CASE(test_detect_conflicting_value)
 
 BOOST_AUTO_TEST_CASE(test_detect_inhomogeneous_array)
 {
+#ifdef TOML11_USE_UNRELEASED_TOML_FEATURES
+    BOOST_TEST_MESSAGE("heterogeneous array will be allowed in the next release");
+#else
     std::istringstream stream(std::string(
             "a = [1, 1.0]\n"
             ));
     BOOST_CHECK_THROW(toml::parse(stream), toml::syntax_error);
+#endif
 }
 
 BOOST_AUTO_TEST_CASE(test_detect_appending_array_of_table)