Bug 33028: (follow-up) Lower the two digits requirement

Bug 33028: (follow-up) Lower the two digits requirement

This patch makes the code not require two decimal digits, as the main
intention here is to forbid (locale) formatted strings to reach the DB.

The number of digits we support needs to be discussed on its own bug,
and a centralized check implemented.

This patch fixes tests:

prove t/db_dependent/Circulation.t
t/db_dependent/Circulation.t .. 1/67 Exception 'Koha::Exceptions::CirculationRule::NotDecimal' thrown 'The circulation rule expected a decimal value' with name => fine, value => 0.1
t/db_dependent/Circulation.t .. Dubious, test returned 11 (wstat 2816, 0xb00)
Failed 53/67 subtests

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>