add colorbar and title to Yang et al. 2018: fig2/d; sort out pint units and clean up code

[AgnieszkaZaba]

Addresses #1744

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.62%. Comparing base (fb79136) to head (ad1a593).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1750   +/-   ##
=======================================
  Coverage   86.62%   86.62%           
=======================================
  Files         413      413           
  Lines       10471    10471           
=======================================
  Hits         9070     9070           
  Misses       1401     1401           

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[slayoo]

Thanks @AgnieszkaZaba !
Let's also add units. In the paper, these are cm^-3 um^-1 with values from 0 to 100 (https://acp.copernicus.org/articles/18/7313/2018/acp-18-7313-2018-f02.png):

[AgnieszkaZaba]

added issue to devops_tests (open-atmos/devops_tests#60) about failing devops_test run due to TODO phrase in output file

[slayoo]

the failure was intriguing... it tried to compile the freshly released Numba 0.63.0, but it should not as we have the [CI_version_pins] variant... which was not used in the readme_snippets.yml workflow! nice catch!