Update test_exercise_3.py

[jcarnaxide]

#743 testing in Python version 3.13, the solution uses a bit more memory than previously in Python version 3.12.

I saw an increase up to about 170MB of memory used for my run.

The provided example which is meant to use too much memory uses about 740MB.

So I think a new threshold of 200MB should be sufficient. This will also be backwards compatible.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 92.82%. Comparing base (9884c9d) to head (061e0c9).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #754      +/-   ##
==========================================
- Coverage   92.94%   92.82%   -0.12%     
==========================================
  Files          95       95              
  Lines       11686    11686              
  Branches      407      407              
==========================================
- Hits        10861    10848      -13     
- Misses        825      838      +13     

Flag	Coverage Δ
cpp	92.82% <ø> (-0.12%)	:arrow_down:
python_and_cython	92.82% <ø> (-0.12%)	:arrow_down:

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