[FIX] mass_mailing_sms: leftover reference to a renamed model

closes odoo/odoo#39874

X-original-commit: c34f860548b0d68773b25e89fb99aad1fb144b8c
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/mass_mailing_sms/models/mailing_mailing.py

@@ -133,7 +133,7 @@ class Mailing(models.Model):
         self.ensure_one()
         opt_out = []
         target = self.env[self.mailing_model_real]
-        if self.mailing_model_real == "mail.mass_mailing.contact":
+        if self.mailing_model_real == 'mailing.contact':
             # if user is opt_out on One list but not on another
             # or if two user with same email address, one opted in and the other one opted out, send the mail anyway
             # TODO DBE Fixme : Optimise the following to get real opt_out and opt_in