SelectionValidationError when creating menu entry with timesheet icon

When initializing a custom module we get the following error:

======================================================================
ERROR: setUpClass (test_module.ProjectTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/pokoli/projectes/tryton/trytond/trytond/convert.py", line 464, in parse_xmlstream
    self.sax_parser.parse(source)
  File "/usr/lib/python3.11/xml/sax/expatreader.py", line 111, in parse
    xmlreader.IncrementalParser.parse(self, source)
  File "/usr/lib/python3.11/xml/sax/xmlreader.py", line 125, in parse
    self.feed(buffer)
  File "/usr/lib/python3.11/xml/sax/expatreader.py", line 217, in feed
    self._parser.Parse(data, isFinal)
  File "/usr/src/debug/python/Python-3.11.3/Modules/pyexpat.c", line 468, in EndElement
  File "/usr/lib/python3.11/xml/sax/expatreader.py", line 336, in end_element
    self._cont_handler.endElement(name)
  File "/home/pokoli/projectes/tryton/trytond/trytond/convert.py", line 519, in endElement
    self.taghandler = self.taghandler.endElement(name)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pokoli/projectes/tryton/trytond/trytond/convert.py", line 170, in endElement
    self.mh.import_record('ir.ui.menu', self.values, self.xml_id)
  File "/home/pokoli/projectes/tryton/trytond/trytond/convert.py", line 695, in import_record
    self.create_records(model, [values], [fs_id])
  File "/home/pokoli/projectes/tryton/trytond/trytond/convert.py", line 701, in create_records
    records = Model.create(vlist)
              ^^^^^^^^^^^^^^^^^^^
  File "/home/pokoli/projectes/tryton/trytond/trytond/model/modelsql.py", line 262, in wrapper
    return func(cls, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pokoli/projectes/tryton/trytond/trytond/model/modelsql.py", line 963, in create
    cls._validate(sub_records)
  File "/home/pokoli/projectes/tryton/trytond/trytond/transaction.py", line 50, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/home/pokoli/projectes/tryton/trytond/trytond/model/modelstorage.py", line 1502, in _validate
    raise SelectionValidationError(gettext(
trytond.model.modelstorage.SelectionValidationError: The value "tryton-timesheet" for field "Icon" in "Productions / Timesheet" of "UI menu" is not one of the allowed options. -

This can be reproduced with an empty module with the following tryton.cfg:

[tryton]
version=6.8.0
depends:
    ir
    attendance
    analytic_account
    analytic_invoice
    account_asset
    account_credit_limit
    account_es
    account_payment_sepa
    account_statement_aeb43
    account_statement_rule
    notification_email
    purchase
    purchase_request_quotation
    purchase_invoice_line_standalone
    purchase_secondary_unit
    product_cost_fifo
    production_outsourcing
    production_work_timesheet
    timesheet
    timesheet_cost
    sale_amendment
    sale_opportunity
    sale_credit_limit
    sale_invoice_grouping
    sale_supply_production
    stock_supply
xml:
    production.xml

And with the following production.xml:

<?xml version="1.0"?>
<tryton>
    <data>
        <menuitem
            parent="production.menu_production"
            name="Timesheet"
            sequence="24"
            id="menu_timesheet"
            icon="tryton-timesheet"/>
    </data>
</tryton>

This is similar to #12246 (closed) but I can reproduce the issue on latest trunk (and 6.8.1 where the fix is applied).