add redis cluster client tests

[leeym]

I should have done this in https://github.com/mennanov/limiters/pull/48, but I think it is not too late to do it now.

The existing test environment only has single node Redis and there is no Redis cluster. Given that the Redis and Redis cluster may behave differently, I think we should test them separately.

• keep Redis at port 6379 while adding Redis cluster at port 7000-7005
• whenever we test Redis, we test Redis cluster as well

Also run it in two builds:

• remove hash tags in redisKey to reproduce the error CROSSSLOT Keys in request don't hash to the same slot
• add hash tags back in redisKey to show that it works

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 80.05%. Comparing base (9d9ccea) to head (00de771).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #50 +/- ## ======================================= Coverage 80.05% 80.05% ======================================= Files 12 12 Lines 1449 1449 ======================================= Hits 1160 1160 Misses 212 212 Partials 77 77 ```

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[mennanov]

Awesome! Thanks!