🐛(mail) fix team invitation subject not translated

Using format or f-string breaks translations

src/backend/core/models.py

@@ -1057,10 +1057,9 @@ class Invitation(BaseInvitation):
 
     def _get_mail_subject(self):
         """Get the subject of the team invitation."""
-        role = self.get_role_display().lower()
         return gettext(
-            f"[La Suite] You have been invited to become a {role} of a group"
-        )
+            "[La Suite] You have been invited to become a %(role)s of a group"
+        ) % {"role": self.get_role_display().lower()}
 
     def _get_mail_context(self):
         """Get the template variables for the invitation."""

src/backend/core/tests/test_models_invitations.py

@@ -246,9 +246,8 @@ def test_models_team_invitations_email():
     # pylint: disable-next=no-member
     assert len(mail.outbox) == 0
 
-    # Please add test for french language after translations update
     invitation = factories.InvitationFactory(
-        role="member", team=team, email="john@people.com", issuer__language="en-us"
+        role="member", team=team, email="john@people.com", issuer__language="fr-fr"
     )
 
     # pylint: disable-next=no-member
@@ -259,13 +258,12 @@ def test_models_team_invitations_email():
 
     assert email.to == [invitation.email]
     assert (
-        email.subject
-        == "[La Suite] You have been invited to become a member of a group"
+        email.subject == "[La Suite] Vous avez été invité(e) à être membre d'un groupe"
     )
 
     email_content = " ".join(email.body.split())
     assert (
-        f"""You have been invited to be a member of the group "{team.name}" within La Suite."""
+        f"""Vous avez été invité(e) à être membre du groupe "{team.name}" au sein de la Suite."""
         in email_content
     )
     assert "[//example.com]" in email_content

src/backend/locale/fr_FR/LC_MESSAGES/django.po

@@ -324,8 +324,8 @@ msgstr "Invitations d'équipe"
 
 #: build/lib/core/models.py:1062 core/models.py:1062
 #, python-brace-format
-msgid "[La Suite] You have been invited to become a {role} of a group"
-msgstr "[La Suite] Vous avez été invité(e) à être {role} d'un groupe"
+msgid "[La Suite] You have been invited to become a %(role)s of a group"
+msgstr "[La Suite] Vous avez été invité(e) à être %(role)s d'un groupe"
 
 #: build/lib/mailbox_manager/admin.py:17 mailbox_manager/admin.py:17
 msgid "Synchronise from dimail"