Bump django-ratelimit from 0.6.0 to 2.0.0

Bumps [django-ratelimit](https://github.com/jsocol/django-ratelimit) from 0.6.0 to 2.0.0.
- [Release notes](https://github.com/jsocol/django-ratelimit/releases)
- [Changelog](https://github.com/jsocol/django-ratelimit/blob/master/CHANGELOG)
- [Commits](jsocol/django-ratelimit@v0.6.0...v2.0.0)

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

requirements/base.txt

@@ -14,7 +14,7 @@ django-extensions==1.7.6
 django-localflavor==3.0.1
 django-markdown-deux==1.0.5
 django-model-utils==2.3.1
-django-ratelimit==0.6.0
+django-ratelimit==2.0.0
 Django==2.2.12
 djangorestframework==3.5.4
 gocardless_pro==1.1.0