🧪(backend) fix unreachable assertion after expected exception

Remove assertion statement that was placed after code expected to raise an
exception. The assertion was never evaluated due to the exception flow,
making the test ineffective.

src/backend/core/tests/rooms/test_api_rooms_invite.py

@@ -230,15 +230,14 @@ def test_api_rooms_invite_error(mock_invite_to_room):
 
     data = {"emails": ["toto@yopmail.com", "toto@yopmail.com"]}
 
-    with pytest.raises(InvitationError) as excinfo:
+    with pytest.raises(InvitationError):
         client.post(
             f"/api/v1.0/rooms/{room.id}/invite/",
             json.dumps(data),
             content_type="application/json",
         )
 
-        mock_invite_to_room.assert_called_once()
-        assert "Could not send invitation" in str(excinfo.value)
+    mock_invite_to_room.assert_called_once()
 
 
 @mock.patch("core.services.invitation.send_mail")