Ray >=2.5 will not support Python 3.6

[jjyao]

Python 3.6 end-of-life (EOL) is 23 Dec 2021 and Ray will drop the support with the following plan:

• Ray 2.4 will be the last version that supports Python 3.6.
• Ray 2.5 (will be released around the end of May 2023) will no longer have Python 3.6 wheels for installation.

[ollie-iterators]

I saw something about Python 3.5 in the file "python/ray/_private/thirdparty/pathspec/compat.py"

[jjyao]

Ray 2.5 is released and Python 3.6 support is dropped.