[FIX] subscription_oca: product-subscription_template company issues

Make company required on subscription_template.

Make subcription_template_id a company-dependent field
on product_template.

subscription_oca/models/product_template.py

@@ -8,5 +8,7 @@ class Product(models.Model):
 
     subscribable = fields.Boolean(string="Subscribable product")
     subscription_template_id = fields.Many2one(
-        comodel_name="sale.subscription.template", string="Subscription template"
+        comodel_name="sale.subscription.template",
+        string="Subscription template",
+        company_dependent=True,
     )

subscription_oca/models/sale_subscription_template.py

@@ -46,6 +46,7 @@ class SaleSubscriptionTemplate(models.Model):
     company_id = fields.Many2one(
         "res.company",
         "Company",
+        required=True,
         default=lambda self: self.env.company,
         domain=lambda self: [("id", "in", self.env.companies.ids)],
     )