update link for sidekiq issue

[tannalynn]

the url test was failing with:

  1) Failure:
HealthyUrlsTest#test_all_urls [/opt/hostedtoolcache/Ruby/3.4.1/x64/lib/ruby/gems/3.4.0/gems/minitest-5.3.3/lib/minitest/assertions.rb:129]:
1 URLs were unreachable!

  https://github.com/mperham/sidekiq/issues/5076 - HTTP 404: Not Found
    files: /home/runner/work/newrelic-ruby-agent/newrelic-ruby-agent/lib/new_relic/agent/instrumentation/sidekiq/extensions/delayed_class.rb.
Expected {"https://github.com/mperham/sidekiq/issues/5076" => "HTTP 404: Not Found"} to be empty.

Looks like the link has changed, so i updated it here.

old: https://github.com/mperham/sidekiq/issues/5076
new: https://github.com/sidekiq/sidekiq/issues/5076

[github-actions]

SimpleCov Report

	Coverage	Threshold
Line	93.59%	93%

[kaylareopelle]

Thank you!