Fix deprecated method and testing

[leedrum]

changes:

• gem minitest has changed the name of the module from MiniTest to Minitest
• method zrangebyscore of Redis is deprecated. It should be zrange with 1 more params ("BYSCORE")
• The Sidekiq config has been changed (reverted, we will support Sidekiq 7.x later)
• Change Sidekiq URL to match Redis default config at local.
• Refacto typos

before fixing:

Finished in 0.088193s, 430.8732 runs/s, 0.0000 assertions/s.
38 runs, 0 assertions, 0 failures, 37 errors, 0 skips

after fixing:

Run options: --seed 40605

# Running:

......................................

Finished in 0.181538s, 209.3226 runs/s, 947.4600 assertions/s.
38 runs, 172 assertions, 0 failures, 0 errors, 0 skips

[mcasper]

@leedrum Thank you for the contribution! A couple small things to address, and then I think we can get this merged

[leedrum]

@mcasper Thank you for the comments. I have fixed it. Could you take a look?

[mcasper]

Actually I think this needs some slight tweaks: https://rubydoc.info/gems/redis/Redis/Commands/SortedSets#zrange-instance_method

Suggested change

	conn.zrange(Sidekiq::Failures::LIST_KEY, score, score, "BYSCORE")
	conn.zrange(Sidekiq::Failures::LIST_KEY, score.to_i, score.to_i, by_score: true)

[leedrum]

the correct param is byscore
https://github.com/redis/redis-rb/pull/1053/files#diff-be7250cec80fe7f394651422fa93e5305524231d080952fd3bd5cb005102f332R2000

[leedrum]

@mcasper I fixed the comment. tks

[leedrum]

The CI still doesn't pass. I will fix it

[leedrum]

@mcasper I have fixed the comments and the CI run successfully.
Take a look when you have time