Bump django-csp from 3.5 to 3.6

Bumps [django-csp](https://github.com/mozilla/django-csp) from 3.5 to 3.6.
- [Release notes](https://github.com/mozilla/django-csp/releases)
- [Changelog](https://github.com/mozilla/django-csp/blob/master/CHANGES)
- [Commits](https://github.com/mozilla/django-csp/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements/base.txt

@@ -2,7 +2,7 @@ Django==2.2.8
 django-bootstrap3==12.0.3
 dj-database-url==0.5.0
 dj-static==0.0.6
-django-csp==3.5
+django-csp==3.6
 django-csp-reports==1.3
 django-crispy-forms==1.8.1
 django-filter==2.2.0