Sidekiq job_version NoMethodError

Summary

The newly added job_version for Sidekiq jobs is not accessible under mailer's ActiveJob wrapper and caused NoMethodError.

Steps to reproduce

Example Project

What is the current bug behavior?

Error is raised when processing jobs

What is the expected correct behavior?

No error should be raised while processing jobs

Relevant logs and/or screenshots

https://sentry.gitlab.net/gitlab/staginggitlabcom/issues/1708702/?query=is%3Aunresolved

Output of checks

This bug happens on staging.GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)