Fixed mismatched-tags warning

include/DeviceModule.h

@@ -268,7 +268,7 @@ namespace ChimeraTK {
 
     friend class Application;
     friend struct history::ServerHistory;
-    friend class detail::DeviceModuleProxy;
+    friend struct detail::DeviceModuleProxy;
 
     template<typename T>
     friend class ExceptionHandlingDecorator;