restricted: Fix pd migration from erp5 to wendelin

When cleaning up Wendelin from restricted python pandas code
(see https://lab.nexedi.com/levin.zimmermann/wendelin/tree/remove-redundant-pandas),
it turned out that there was one line still missing in erp5.
This missing line caused a failed test in wendelin functional tests:

  https://erp5js.nexedi.net/#/test_result_module/20220614-1B46817BD/6

Readding the line fixed the test.

product/ERP5Type/patches/Restricted.py

@@ -488,6 +488,7 @@ else:
   allow_type(pd.Timestamp)
   allow_type(pd.DatetimeIndex)
   allow_type(pd.MultiIndex)
+  allow_type(pd.Index)
   allow_type(pd.indexes.range.RangeIndex)
   allow_type(pd.indexes.numeric.Int64Index)
   allow_type(pd.core.groupby.DataFrameGroupBy)