Added basic framework for creating cxx20 test cases

tests/test_cases.cc

@@ -255,6 +255,9 @@ using namespace clanguml::test::matchers;
 #include "t00053/test_case.h"
 #include "t00054/test_case.h"
 #include "t00055/test_case.h"
+#if defined(ENABLE_CXX_STD_20_TEST_CASES)
+#include "t00056/test_case.h"
+#endif
 #include "t00057/test_case.h"
 
 ///
@@ -340,4 +343,4 @@ int main(int argc, char *argv[])
     clanguml::util::setup_logging(debug_log ? 3 : 1);
 
     return session.run();
-}
+}