pack_sim: Support the OPM Flow keyword PYACTION

[vkip]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 41.17647% with 10 lines in your changes missing coverage. Please review.

Project coverage is 85.27%. Comparing base (f19cbac) to head (464abec).

Files with missing lines	Patch %	Lines
src/subscript/pack_sim/pack_sim.py	41.17%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #802      +/-   ##
==========================================
- Coverage   85.38%   85.27%   -0.11%     
==========================================
  Files          49       49              
  Lines        7539     7553      +14     
==========================================
+ Hits         6437     6441       +4     
- Misses       1102     1112      +10     

☔ 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.

[alifbe]

Cool 👍

The changes looks good to me. Could you please add a test case as well?