Update example using 'python_requires'

Old `python_requires` is deprecated, we should add an example using the new syntax for `python_requires` and remove current example if it is no longer needed (no links back from the docs or from a blogpost)

Search the examples repository for the current `python_requires` example and inspect whether documentation or blog references still point to it. Confirm the supported new syntax from the surrounding example context, then update or remove the old example and verify that no listed references remain.

Written by the indexing model from the issue text.