Resolve "Update gem sidekiq-cron from 0.4.4 to 0.6.0 and rufus-scheduler from 3.1.10 to 3.4.0"

What does this MR do?

This MR updates sidekiq-cron from 0.4.4 to 0.6.0 and rufus-scheduler from 3.1.10 to 3.4.0. This is motivated from https://gitlab.com/gitlab-org/gitlab-ce/issues/31274#note_28257378. If we updates rufus-scheduler, we must update sidekiq-cron as well, because of sidekiq-cron has a bug with a particular version of rufus-scheduler. This MR's combination is latest and stable.

Related !10948 (merged)

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Changelogs for each gem

1. sidekiq-cron - https://github.com/ondrejbartas/sidekiq-cron/blob/master/Changes.md
2. rufus-scheduler - https://github.com/jmettraux/rufus-scheduler/blob/master/CHANGELOG.txt
3. et-orbi - https://github.com/floraison/et-orbi/blob/master/CHANGELOG.md
4. tzinfo - https://github.com/tzinfo/tzinfo/blob/master/CHANGES.md

sidekiq-cron depends on rufus-scheduler. rufus-scheduler depends on et-orbi. et-orbi depends on tzinfo.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #31554 (closed)

/cc @grzesiek @stanhu