Add resque-scheduler 5 support

[and9000]

Hello,

resque-retry depends on resque-scheduler version ~> 4.0 but it's master branch (which contains useful fixes like this) already bumped version 5.

This PR enables using master's branch of resque-scheduler with resque-retry.

I've tested this PR locally adding gem 'resque-scheduler', github: 'resque/resque-scheduler' to the Gemfile and everything is green (I don't know how to include this test on the testsuite, please suggests me).

Thanks,
Andrea

[jzaleski]

@and9000 from a test-coverage perspective, I think we're alright. However since you added ruby-3.0 support w/ #170, could you please re-base it in so we test against 3.0 here as well?

[and9000]

@and9000 from a test-coverage perspective, I think we're alright. However since you added ruby-3.0 support w/ #170, could you please re-base it in so we test against 3.0 here as well?

Sure, done!

[jzaleski]

LGTM