Bug 18766: Remove itemtype-related warnings from ArticleRequests.t

This patch fixes a small mistake on that test file (itype vs. itemtype
in itemtypes table)

To test:
- Run:
  $ sudo koha-shell kohadev
 k$ cd kohaclone
 k$ prove t/db_dependent/ArticleRequests.t
=> FAIL: itemtype-related warning displayed
- Apply the patch
- Run
 k$ prove t/db_dependent/ArticleRequests.t
=> SUCCESS: No warnings, YAY!
- Sign off :-D

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

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

t/db_dependent/ArticleRequests.t

@@ -58,7 +58,7 @@ my $item = Koha::Item->new(
     {
         biblionumber     => $biblio->id,
         biblioitemnumber => $biblioitem->id,
-        itype => $itype->{itype},
+        itype => $itype->{itemtype},
     }
 )->store();
 ok( $item->id, 'Koha::Item created' );