Update utils to 12.0.0

Includes:

- [x] https://github.com/alphagov/notifications-utils/pull/94 (breaking
      changes which are responsible for all the changes to the API in
      this PR)

The test for `get_sms_fragment_count` has been removed because this
method is already tested in utils here:

ac20f7e99e/tests/test_base_template.py (L140-L159)

tests/app/notifications/rest/test_send_notification.py

@@ -129,7 +129,7 @@ def test_send_notification_with_placeholders_replaced(notify_api, sample_email_t
                 queue="send-email"
             )
             assert response.status_code == 201
-            assert response_data['body'] == 'Hello Jo\nThis is an email from GOV.UK'
+            assert response_data['body'] == u'Hello Jo\nThis is an email from GOV.\u200BUK'
             assert response_data['subject'] == 'Jo'
 
 

tests/app/notifications/test_process_notification.py

@@ -18,14 +18,14 @@ from tests.app.conftest import sample_notification, sample_template, sample_emai
 def test_create_content_for_notification_passes(sample_email_template):
     template = Template.query.get(sample_email_template.id)
     content = create_content_for_notification(template, None)
-    assert content.rendered == template.content
+    assert str(content) == template.content
 
 
 def test_create_content_for_notification_with_placeholders_passes(sample_template_with_placeholders):
     template = Template.query.get(sample_template_with_placeholders.id)
     content = create_content_for_notification(template, {'name': 'Bobby'})
     assert content.content == template.content
-    assert 'Bobby' in content.rendered
+    assert 'Bobby' in str(content)
 
 
 def test_create_content_for_notification_fails_with_missing_personalisation(sample_template_with_placeholders):

tests/app/notifications/test_rest.py

@@ -711,7 +711,7 @@ def test_get_notification_by_id_returns_merged_template_content_for_email(
 
         notification = json.loads(response.get_data(as_text=True))['data']['notification']
         assert response.status_code == 200
-        assert notification['body'] == 'Hello world\nThis is an email from GOV.UK'
+        assert notification['body'] == 'Hello world\nThis is an email from GOV.\u200BUK'
         assert notification['subject'] == 'world'
         assert notification['content_char_count'] is None