Disable python unittests for c++98 on mac

(cherry picked from commit 180a55e8)

CI/ci-mac.sh

@@ -165,6 +165,7 @@ echo "Running Python unittests Debug version "
 echo "======================================================================"
 echo -e "${NC}"
 
+if [ "$LANGUAGE" == "C++11" ]; then
 
 # Execute Python unittests
 cd Python-Unittests
@@ -172,3 +173,6 @@ cd Python-Unittests
 rm -f openmesh.so
 cp ../Build/python/openmesh.so .
 python -m unittest discover -v
+else
+  echo "WARNING! Python unittests disabled for clang on Mac with c++98 !!"
+fi