Fix compatibility with Redis <6.2

[ClearlyClaire]

Note that this leaves the possibility of a race condition in which multiple second-factor authentication attempts are performed at the same time and all triggering a mail. This is relatively improbable, though, and would only result in (limited) spam, it would not allow an attacker to avoid sending the mail.

[ClearlyClaire]

cc @kmycode

[kmycode]

Thanks, it works for me.

$ redis-server --version
Redis server v=6.0.16 sha=00000000:0 malloc=jemalloc-5.2.1 bits=64 build=a3fdef44459b3ad6

RAILS_ENV=test bundle exec rspec spec/features/oauth_spec.rb

[renchap]

We will need to remember to revert this once we change our supported redis version

[ClearlyClaire]

It seems that we are again incompatible with Redis < 6.2 because of our Stoplight update.