rename json include folder -> nlohmann

This lets us resolve the include when unsing our library from a 3d party
project. The choosen structure, namely nlohmann/json.hpp can be found in
packages from Fedora, Opensuse, Debian and Ubuntu.

Signed-off-by: Tobias Klausmann <tobias.klausmann@lenze.com>
diff --git a/sdks/c++/basys.sdk.cc/src/include/BaSyx/shared/object/obj_function.h b/sdks/c++/basys.sdk.cc/src/include/BaSyx/shared/object/obj_function.h
index 5acad0b..9902e82 100644
--- a/sdks/c++/basys.sdk.cc/src/include/BaSyx/shared/object/obj_function.h
+++ b/sdks/c++/basys.sdk.cc/src/include/BaSyx/shared/object/obj_function.h
@@ -5,7 +5,7 @@
 
 #include <BaSyx/shared/object/object_header.h>
 
-#include <json/json.hpp>
+#include <nlohmann/json.hpp>
 
 namespace basyx {
 namespace detail {