Remove `PyPlot` dependency in the `examples`

[bvdmitri]

This PR removes the PyPlot dependency from our CI pipeline. The only one example, which was still using PyPlot RTS vs BIFM is now using Plots instead. The primary reason for removing PyPlot is that it often fails to install on CI for unknown reasons and the full build of matplotlib dependencies takes about 8 minutes on each run.

[review-notebook-app[bot]]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (0ec052d) 79.91% compared to head (1bb3696) 79.91%.

:mega: This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #93 +/- ## ======================================= Coverage 79.91% 79.91% ======================================= Files 10 10 Lines 1200 1200 ======================================= Hits 959 959 Misses 241 241 ``` Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biaslab). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biaslab)

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.