[PWGEM/Dilepton] add a task for MC truth (#9842)

Author: dsekihat

PWGEM/Dilepton/Tasks/CMakeLists.txt

@@ -131,3 +131,8 @@ o2physics_add_dpl_workflow(associate-mccollision-to-collision
                     PUBLIC_LINK_LIBRARIES O2::Framework O2Physics::AnalysisCore
                     COMPONENT_NAME Analysis)
 
+o2physics_add_dpl_workflow(study-mc-truth
+                    SOURCES studyMCTruth.cxx
+                    PUBLIC_LINK_LIBRARIES O2::Framework O2Physics::AnalysisCore
+                    COMPONENT_NAME Analysis)
+