python: Path: *.py: Fix python3 syntax

src/Mod/Path/PathScripts/centroid_post.py

@@ -73,7 +73,7 @@ def export(selection,filename,argstring):
     params = ['X','Y','Z','A','B','I','J','F','H','S','T','Q','R','L'] #Using XY plane most of the time so skipping K
     for obj in selection:
         if not hasattr(obj,"Path"):
-            print "the object " + obj.Name + " is not a path. Please select only path and Compounds."
+            print("the object " + obj.Name + " is not a path. Please select only path and Compounds.")
             return
     myMachine = None
     for pathobj in selection: