[FIX] purchase_product_matrix: wrong category

closes odoo/odoo#35543

Signed-off-by: Damien Bouvy (dbo) <dbo@odoo.com>

addons/purchase_product_matrix/__manifest__.py

@@ -9,7 +9,7 @@
         This module allows to fill Purchase Orders rapidly
         by choosing product variants quantity through a Grid Entry.
     """,
-    'category': 'Sales',
+    'category': 'Purchase',
     'version': '1.0',
     'depends': ['purchase', 'product_matrix'],
     'data': [