Fix OverflowError when calculating datetime.min date for left-hand TZs

[xispa]

Description of the issue/feature this PR addresses

This Pull Request fixes the following issue when validating a max_date in a Timezone that is before GMT+0:

Pdb++) value
'2023-10-02T00:00'
(Pdb++) max_date
DateTime('9999/12/31 23:59:59.999999 US/Central')
(Pdb++) dtime.to_ansi(value)
'20231002000000'
(Pdb++) dtime.to_ansi(max_date)
*** OverflowError: date value out of range
(Pdb++) dtime.to_ansi(dtime.datetime.min)
'00010101000000'
(Pdb++) dtime.to_ansi(dtime.datetime.max)
'99991231235959'

Current behavior before PR

Traceback when validating max dates in TZ that are on the left-hand of GMT+0

Traceback (innermost last):
  Module ZPublisher.WSGIPublisher, line 176, in transaction_pubevents
  Module ZPublisher.WSGIPublisher, line 385, in publish_module
  Module ZPublisher.WSGIPublisher, line 288, in publish
  Module ZPublisher.mapply, line 85, in mapply
  Module ZPublisher.WSGIPublisher, line 63, in call_object
  Module bika.lims.decorators, line 51, in decorator
  Module bika.lims.browser.analysisrequest.add2, line 708, in __call__
  Module bika.lims.browser.analysisrequest.add2, line 1753, in ajax_submit
  Module senaite.core.browser.fields.datetime, line 77, in validate
  Module senaite.core.browser.fields.datetime, line 117, in validate_max_date
  Module senaite.core.api.dtime, line 205, in to_ansi
  Module senaite.core.api.dtime, line 166, in to_dt
  Module senaite.core.api.dtime, line 320, in to_zone
  Module pytz.tzinfo, line 328, in localize
  Module pytz.tzinfo, line 254, in normalize
OverflowError: date value out of range

Desired behavior after PR is merged

No traceback when validating max dates in TZ that are on the left-hand of GMT+0

--
I confirm I have tested this PR thoroughly and coded it according to PEP8
and Plone's Python styleguide standards.