Bug 36081: (QA follow-up) Resolve IsNotDebit exception in ArticleRequests.t

Resolve (when running ArticleRequests.t):
Exception 'Koha::Exceptions::Account::IsNotDebit' thrown 'Account line 326 is not a debit'

This occurs after switching from ArticleRequest->new to TestBuilder.
TestBuilder creates an account line that has a credit_type_code and
a debit_type_code. (This could be fixed further somewhere else.)
For now, just setting debit_id to NULL.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>
(cherry picked from commit a8078a4f3d)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>

t/db_dependent/ArticleRequests.t

@@ -77,6 +77,7 @@ my $article_request = $builder->build_object(
             biblionumber   => $item->biblionumber,
             itemnumber     => $item->itemnumber,
             title          => $article_request_title,
+            debit_id       => undef,
         }
     }
 )->request();