remove workaround (#579)

Author: Barthelemy

Modules/ITS/include/ITS/ITSFeeTask.h

@@ -22,11 +22,6 @@
 #include <TH1.h>
 #include <TH2.h>
 
-// TODO actually fix the problem instead of disabling the warning
-#if defined(__clang__)
-#pragma clang diagnostic ignored "-Wnested-anon-types"
-#endif
-
 class TH2I;
 class TH1I;