core: fix pylint warnings

these ERP5 Python Scripts were not covered by coding style tests

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/TemplateTool_filterClassTupleDiff.py

@@ -3,6 +3,6 @@ if len(old_line_list) == 4 and len(new_line_list) == 1 and \
    old_line_list[2] == '<tuple/>' and \
    old_line_list[3] =='</tuple>' and \
    old_line_list[1]== new_line_list[0]:
-    return True
+  return True
 
 return False

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/TemplateTool_filterOOBTreeClassDiff.py

 if len(old_line_list) == 1 and len(new_line_list) == 1 and \
    new_line_list[0] == old_line_list[0].replace("BTrees._OOBTree","BTrees.OOBTree"):
-    return True
+  return True
 
 return False

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/TemplateTool_filterPortalTypeClassDiff.py

@@ -6,12 +6,12 @@ new_group_list = new_line.split('"')
 if len(new_group_list) != 5:
   return False
 
-before, portal_type, module, erp5_portal_type, after = new_group_list
+before, _, module, erp5_portal_type, after = new_group_list
 if before != '<global name=' or module != ' module=' or erp5_portal_type != 'erp5.portal_type' or after != '/>':
   return False
 
 old_group_list = old_line_list[0].split('"')
 if len(old_group_list) == 5:
-  before2, ignore, module2, products_erp5type, after2 = old_group_list
+  before2, _, module2, products_erp5type, after2 = old_group_list
   return before2 == before and module2 == module and products_erp5type.startswith("Products.ERP5Type.Document.") and after2 == after
 return False