Improve bookmark form accessibility (#1116)

* Bump Django

* Render error messages in English

* Remove unused USE_L10N option

* Associate errors and help texts with form fields

* Make checkbox inputs clickable

* Change cancel button text

* Fix tests

bookmarks/templates/shared/error_list.html

@@ -0,0 +1,6 @@
+{% load i18n %}
+
+{# Force rendering validation errors in English language to align with the rest of the app #}
+{% language 'en-us' %}
+{% if errors %}<ul class="{{ error_class }}"{% if errors.field_id %} id="{{ errors.field_id }}_error"{% endif %}>{% for error in errors %}<li>{{ error }}</li>{% endfor %}</ul>{% endif %}
+{% endlanguage %}