Bump vendored Sidekiq gem to 7.2.4

Context: https://gitlab.com/gitlab-org/distribution/team-tasks/-/issues/1591#note_2068795383

Referencing MR which introduced Sidekiq 7.1.6 with Redis 6.0 compat changes: !142986 (merged)

Key changes

1. Vendor Sidekiq 7.2.4 gem.
2. Add Redis 6.0 compatibility changes.
3. Ensure Redis 6.0 commands are tested.
4. Update NOTICE.txt
5. Drop vendored Sidekiq 7.1.6