Bug 20015: use Modern::Perl in Serials perl script

Bug 20015: use Modern::Perl in Serials perl script

Test plan:
Check that use strict; use warnings; doesn't exist in the following
files and use Modern::Perl; is written instead.
acqui-search-result.pl
acqui-search.pl
checkexpiration.pl
reorder_members.pl
routing-preview.pl
routing.pl
serials-collection.pl
serials-edit.pl
subscription-add.pl
subscription-bib-search.pl
subscription-renew.pl
viewalerts.pl

Signed-off-by: Jon Knight <J.P.Knight@lboro.ac.uk>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>