Guarantee order of PWG items in Data Model menue (#7353)

Author: pbuehler

scripts/datamodel-doc/ALICEO2includeFile.py

@@ -672,7 +672,7 @@ def printHTML(self):
 
     # PWG data model names
     dmnames = [CERsPWG[i][4] for i in list(range(0, len(CERsPWG)))]
-    dmnames = list(set(dmnames))
+    dmnames = np.unique(dmnames)
     for dmname in dmnames:
       print("")
       print("##", dmname)