Bump Django 2.2.13

Sur la mailing list django-announce :

Django versions 3.0.7 and 2.2.13 will be released on Wednesday, June 3, 2020 around 1000 UTC.
They will fix two security defects with severity of "medium" and "low".

added 1 deleted label

changed due date to June 04, 2020

Released: https://www.djangoproject.com/weblog/2020/jun/03/security-releases/

mentioned in merge request !774 (merged)

assigned to @erwanrouchet

closed via merge request !774 (merged)

mentioned in commit 41f86099