[-release]Preparing version 6.2.56, again

A module couldn't compile without optional dependency.

src/lib/Sympa/Test/MockLDAP.pm

@@ -5,7 +5,7 @@ package Sympa::Test::MockLDAP;
 
 use strict;
 use warnings;
-use Test::Net::LDAP::Util qw(ldap_mockify);
+BEGIN { eval 'use Test::Net::LDAP::Util qw(ldap_mockify)'; }
 
 use Sympa::DatabaseDriver::LDAP;