Bug 28632: Prevent api/v1/patrons.t to fail on dates comparison

Bug 28632: Prevent api/v1/patrons.t to fail on dates comparison

 #   Failed test 'Returned patron from update matches expected'
 #   at t/db_dependent/api/v1/patrons.t line 537.
 #     Structures begin differing at:
 #          $got->{updated_on} = '2021-07-27T13:33:53+00:00'
 #     $expected->{updated_on} = '2021-07-27T13:33:52+00:00'
 # Looks like you failed 1 test of 42.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>