Fix CI by downgrading OS image

[reneSchm]

Changes and Information

Please briefly list the changes (main added features, changed items, or corrected bugs) made:

• Downgrade from ubuntu-latest (recently updated from 22.04 to 24.04) back to ubuntu-22.04
• Remove PyQt6 dependency from py-epidata, as the version provided by image manylinux_2_28_x86_64 now breaks with python versions 3.8 and older.

If need be, add additional information and what the reviewer should look out for in particular:

• While the epidata CI runs on ubuntu, parts use manylinux_2_28_x86_64 (AlmaLinux 9, not Debian based) via docker.
• The PyPI pages of PyQt6 and PyQt6-sip suggest they should work with 3.8 and newer.
• PyQt6-sip changed versions from the last successful Epidata-CI
  (v13.8) to the first failing Epidata-CI (v13.9). See line 139 in the respective CI.
• We use PyQt as matplotlib backend (mpl_backend = QtAgg in epidata/download_config.conf), which is not tested by the CI, so it should be added back later.

Merge Request - Guideline Checklist

Please check our git workflow. Use the draft feature if the Pull Request is not yet ready to review.

Checks by code author

• Every addressed issue is linked (use the "Closes #ISSUE" keyword below)
• New code adheres to coding guidelines
• No large data files have been added (files should in sum not exceed 100 KB, avoid PDFs, Word docs, etc.)
• Tests are added for new functionality and a local test run was successful (with and without OpenMP)
• Appropriate documentation for new functionality has been added (Doxygen in the code and Markdown files if necessary)
• Proper attention to licenses, especially no new third-party software with conflicting license has been added
• (For ABM development) Checked benchmark results and ran and posted a local test above from before and after development to ensure performance is monitored.

Checks by code reviewer(s)

• Corresponding issue(s) is/are linked and addressed
• Code is clean of development artifacts (no deactivated or commented code lines, no debugging printouts, etc.)
• Appropriate unit tests have been added, CI passes, code coverage and performance is acceptable (did not decrease)
• No large data files added in the whole history of commits(files should in sum not exceed 100 KB, avoid PDFs, Word docs, etc.)
• On merge, add 2-5 lines with the changes (main added features, changed items, or corrected bugs) to the merge-commit-message. This can be taken from the briefly-list-the-changes above (best case) or the separate commit messages (worst case).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.92%. Comparing base (3a06d82) to head (cb1adc9).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1160      +/-   ##
==========================================
- Coverage   96.98%   96.92%   -0.06%     
==========================================
  Files         142      148       +6     
  Lines       11874    13570    +1696     
==========================================
+ Hits        11516    13153    +1637     
- Misses        358      417      +59     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[reneSchm]

Again the CI fails due to indirect code coverage changes. I wonder if these are caused by un-mocked RNGs?