Bug 9032: (follow-up) add new dependency Email::Valid

Bug 9032: (follow-up) add new dependency Email::Valid

Just adds this dependency to PerlDependencies module.
Note from Robin: libemail-valid-perl is in squeeze already.

Test plan:
You should see Email::Valid now under About/Perl modules.
If Email::Valid is not yet installed on your system, please do so.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Dobrica Pavlinusic <dpavlin@rot13.org>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>