Avoid in-place Python code execution

[pavoljuhas]

Address https://github.com/quantumlib/Cirq/security/code-scanning/645

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.37%. Comparing base (9550c0d) to head (b6f1c96).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7667   +/-   ##
=======================================
  Coverage   99.37%   99.37%           
=======================================
  Files        1082     1082           
  Lines       96691    96691           
=======================================
  Hits        96086    96086           
  Misses        605      605           

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