Update middleman to 4.4.2 to receive build performance increase

Merged David Barr requested to merge davebarr/www-gitlab-com:12405-upgrade-middleman into master

Why is this change being made?

As described in #12405 (closed), I was able to shave off over a minute on the handbook build time by resolving an upstream regular expression issue. This should hopefully help with local build times as well as removing unnecessary CPU cycles in pipelines. :)

Why not wait for the next release of middleman? New releases are fairly infrequent, so accepting this MR would depend if you think it's worth using a GitHub ref for the performance improvement or not in the meantime.

edit: The new release of middleman is now available (4.4.2). This MR runs bundle update middleman

Author Checklist

  • Provided a concise title for the MR
  • Added a description to this MR explaining the reasons for the proposed change, per say-why-not-just-what
    • Copy/paste the Slack conversation to document it for later, or upload screenshots. Verify that no confidential data is added.
  • Assign reviewers for this change to the correct DRI(s)
    • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the "Maintained by" section in on the page being edited.
    • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies.
  • If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR.
    • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

Closes #12405 (closed)

Edited by David Barr