Type check ert.gui.plottery

[eivindjahren]

There are a couple of things that are ignored:

1. Axis.x_label typehints says str and not Optional[str], but the code says otherwise.
2. For some reason the ternary operator for calculating min is not caught correctly by mypy. Either that or there is some other reason why it thinks current_min can be None in the call to min.

• [x] PR title captures the intent of the changes, and is fitting for release notes.
• [x] Added appropriate release note label
• [x] Commit history is consistent and clean, in line with the contribution guidelines.
• [x] Make sure tests pass locally (after every commit!)

When applicable

• [ ] When there are user facing changes: Updated documentation
• [ ] New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• [ ] Large PR: Prepare changes in small commits for more convenient review
• [ ] Bug fix: Add regression test for the bug
• [ ] Bug fix: Create Backport PR to latest release

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 89.58333% with 5 lines in your changes missing coverage. Please review.

Project coverage is 86.58%. Comparing base (6e02dfe) to head (0d8803d). Report is 6 commits behind head on main.

Files	Patch %	Lines
src/ert/gui/plottery/plots/cesp.py	72.72%	3 Missing :warning:
src/ert/gui/plottery/plots/std_dev.py	66.66%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #8117 +/- ## ========================================== + Coverage 86.54% 86.58% +0.04% ========================================== Files 383 383 Lines 23721 23802 +81 Branches 618 630 +12 ========================================== + Hits 20529 20610 +81 - Misses 3111 3119 +8 + Partials 81 73 -8 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.