[FIX] website_sale_slides: correct demo data file path

Correctly set demo in demo instead of data.

Related to Issue: 1965630

closes odoo/odoo#32481

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/website_sale_slides/__manifest__.py

@@ -11,8 +11,10 @@
     'installable': True,
     'auto_install': True,
     'data': [
-        'data/website_sale_slides_demo.xml',
         'views/slide_channel_views.xml',
         'views/website_slides_templates.xml',
-    ]
+    ],
+    'demo': [
+        'data/website_sale_slides_demo.xml',
+    ],
 }