chore: gif cleanup for pytests

[abanuelo]

Description

After the simulation.gif has been generated by running the test_newtonian.py file, we should delete this file. Also we should ignore simulation.gif for git version control!

Issue Link

Checklist

• I have tested the changes locally via pytest and/or other means
• I have added or updated relevant documentation
• I have autoformatted the code with black and isort
• I have added test cases (if applicable)

Additional Notes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.30%. Comparing base (d7679fb) to head (1d14751).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #285      +/-   ##
==========================================
- Coverage   91.32%   91.30%   -0.02%     
==========================================
  Files          54       54              
  Lines       13515    13520       +5     
==========================================
+ Hits        12343    12345       +2     
- Misses       1172     1175       +3     

see 4 files with indirect coverage changes