Speed up apt runs by ignoring man pages

[llimeht]

Description

If apt has to do a lot of work (because the base image is out of date, which happens periodically), then it can end up spending a lot of time generating the database of manual pages (trigger for pacakge man-db). If you're unlucky, it takes 30ish seconds on this. We don't need the man pages, so we can ensure this time is not wasted.

How Has This Been Tested?

CI runs

Review Checklist:

[if using the editor, use [x] in place of [ ] to check a box]

Documentation (check at least one)

• There is nothing that needs documenting
• Documentation changes are in this PR
• There is an issue open for the documentation (link?)

Installers

• There is a chance this will affect the installers, if so
  • Windows installer (GH artifact) has been tested (installed and worked)
  • MacOSX installer (GH artifact) has been tested (installed and worked)
  • Wheels installer (GH artifact) has been tested (installed and worked)

Licensing (untick if necessary)

• The introduced changes comply with SasView license (BSD 3-Clause)

[backmari]

This change should speed up the CI pipeline and has been suggested to be added to the GitHub runner images: actions/runner-images#10977