Update python requirement to 3.6.2 or above

[chinyeungli]

I was using python 3.6.0 and have this following error AttributeError: module 'typing' has no attribute 'NoReturn' when running tests related to Jinja2
I found a similar problem here: https://stackoverflow.com/questions/67569038/attributeerror-module-typing-has-no-attribute-noreturn/67857937#67857937 which suggests to use python 3.6.2 or above.

[amittri1025]

How to contribute / solve this issue.. help

[chinyeungli]

I think we just need to update the documentation in the README to use python3.6.2 or above and possibly do some checking in the configure scripts

[Naveen-singla]

@chinyeungli I would like to resolve this issue by making changes in readme documentation can you please assign this task to me