Avoid hardcoding "python" binary name

[stefanor]

On modern Debian systems, there isn't a "python" binary, unless a user is in a virtualenv or has installed python-is-python3.

[codecov-commenter]

Codecov Report

Base: 83.88% // Head: 83.88% // No change to project coverage 👍

Coverage data is based on head (e90e322) compared to base (276ae10).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #83   +/-   ##
=======================================
  Coverage   83.88%   83.88%           
=======================================
  Files          12       12           
  Lines         577      577           
=======================================
  Hits          484      484           
  Misses         93       93           

Impacted Files	Coverage Δ
tests/test_cppimport.py	98.55% <ø> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[tbenthompson]

Thanks! This is perfect.