Going towards the end of life of Python2 (18 months from now), we should start having CI vote -1/-2 if there is any new python2 files pushed in the repository.
Of course this is pretty easy to be done just checking the shebang, while might be impossible for scripts that don't have a shebang26570726f6475636520796f757220627567207573696e67206120726563656e742076657273696f6e206f662074686520736f6674776172652c20746f2068652077696b6920636f6e74656e74206c616e67756167652e0a0a5468616e6b20796f752e0a546167730a436865636b557365720ad70a436f6e6e65637465642d4f70656e2d48657269746167652d42617463682d75706c6f61647320285241c42d4b4d425f315f323031372d3032290ad70a54616d696c2d53697465730ad70a47616d6570726573730ad70a48617368746167730ad70a4a4144450ad70a4b6172746f456469746f720ad70a4c616e67756167652d323031382d4170722d4a756e650ad70a4e65772d456469746f722d457870657269656e6365730ad70a4d61696c0ad70a5443422d5465616d0ad70a53756273637269626572730a4465736372697074696f6e20507265766965770a436f6e74656e77a6f6e652073657474696e6720696e20796f75722070726f66696c652c20636c69636b20746f207265636f6e63696c652e