Hi,
The python-tests.el will fail on finding interpreter "python" for
there is no "python"  on CentOS8, Ubuntu 20.04,  only "python3" exists
after installation.

And the patch will try to search python/python3/python2 as the python
testing interpreter; it also support a env var
"EMACS_PYTHON_INTERPRETER" to switch between different version of
python (eg: python3.6, python3.11, ...).

Please help review the  enhancement in "python-tests.el". Thanks.