[k4run] ensure no duplicates are in the list of configurables

With some job configurations, some tools are part of this list twice, and then raise an argumenterror when k4run tries to add their properties as command line arguments

k4FWCore/scripts/k4run

@@ -70,7 +70,7 @@ if __name__ == "__main__":
       option_db = {}
 
       # loop over all components that were configured in the options file
-      for conf in list(ApplicationMgr.allConfigurables.values()):
+      for conf in set(list(ApplicationMgr.allConfigurables.values())):
         # skip public tools and the applicationmgr itself
         if "ToolSvc" not in conf.name() and "ApplicationMgr" not in conf.name():
           props = conf.getPropertiesWithDescription() #dict propertyname: (propertyvalue, propertydescription)