Use a canonical Python3 version

[tcanabrava]

The current check differs from file to file, some require python, some require python3.8. The current version of python is 3.10, and it's backward compatible, so we only need to test if a python version is below python3.8 before bailing out.

This future proofs the code and allows linux distros and windows installations to use newer python versions.

[osubboo]

We cannot accept this solution due to internal Python deployment ( uses 3.6, which is not sufficient ). This issue was addressed in new version on bde build system ( see bbs_build_env/bbs_build wrappers ). The documentation for those tools will be deployed shortly.