Fix assertions when we catch an error in the tests

Code that is within a `with Python.raises(...)` context manager but
comes after the line that raises the exception doesn't get evaluated.
We had some assertions that we never being tested because of this, so
this ensures that they will always get run and fixes them where
necessary.

tests/app/celery/test_provider_tasks.py

@@ -65,7 +65,7 @@ def test_should_go_into_technical_error_if_exceeds_retries_on_deliver_sms_task(s
 
     with pytest.raises(NotificationTechnicalFailureException) as e:
         deliver_sms(sample_notification.id)
-        assert sample_notification.id in e.value
+    assert str(sample_notification.id) in str(e.value)
 
     provider_tasks.deliver_sms.retry.assert_called_with(queue="retry-tasks", countdown=0)
 
@@ -78,7 +78,7 @@ def test_should_go_into_technical_error_if_exceeds_retries_on_deliver_email_task
 
     with pytest.raises(NotificationTechnicalFailureException) as e:
         deliver_email(sample_notification.id)
-        assert sample_notification.id in e.value
+    assert str(sample_notification.id) in str(e.value)
 
     provider_tasks.deliver_email.retry.assert_called_with(queue="retry-tasks")
     assert sample_notification.status == 'technical-failure'