Update to Rack Attack v5.3.0+
The current version of Rack Attack we are using (v4.4.1) doesn't support Rails' 5.2 ActiveSupport::Cache::RedisCacheStore
: https://github.com/kickstarter/rack-attack/issues/281. This caused 500 errors in https://gitlab.com/gitlab-org/gitlab-ce/issues/66449.
We'll need to update it to v5.3.0 to get the fix for this: https://github.com/kickstarter/rack-attack/pull/340 (and maybe https://github.com/kickstarter/rack-attack/pull/350). Note that v6.0.0 is out (https://github.com/kickstarter/rack-attack/releases), so we could use that too.
Edited by Stan Hu