Bug 22641: Use raw filter on html slip

Bug 22641: Use raw filter on html slip

To test:
Enable SCO
Load a patron
Hit finish, print slip
Note slip shows as raw html
Apply patch
Repeat, get a correctly formatted slip

Signed-off-by: Liz Rea <wizzyrea@gmail.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
https://bugs.koha-community.org/show_bug.cgi?id=22068

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 247d0d1df1ee5cc7f3184d8ac6ab35373af739b3)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>