Drop support for Python 3.5

[Tim Graham]

Django 2.2 LTS, supported until April 2022, is the last version to support Python 3.5 (end of life: September 2020).

[Tim Graham]

​PR

[Claude Paroz]

I'm not so enthusiast to drop Python 3.5 now (it is still the default version in Debian stable). Couldn't this be done in Django 3.1 instead?

[Tim Graham]

If that's the consensus, I guess we should rewrite ​our policy about Python version support and instead base it on Debian (you made ​the same argument about Python 3.4 support).

Typically, we will support a Python version up to and including the first Django LTS release whose security support ends after security support for that version of Python ends. For example, Python 3.3 security support ends September 2017 and Django 1.8 LTS security support ends April 2018. Therefore Django 1.8 is the last version to support Python 3.3.

[Claude Paroz]

It's not a consensus at all for now, I'm just on the side on the very conservative people wrt long time support software. Feel free to ignore me if I'm on a small minority boat. I'm not vindictive :-)

[Simon Charette]

Thanks for your input Claude. I also think we should stick to our documented policy as well to be coherent with the previous releases.

I'm not too familiar with Debian's package policy but given 2.2 LTS is not going away anytime soon nothing should prevent them from sticking to it until stable defaults to 3.6+?

[Claude Paroz]

Yes, sure, it's more about people willing to contribute to Django master will have to install a custom Python version in current Debian stable (the next one should be out this summer).

[Tim Graham]

I created a ​django-developers discussion regarding the Python version support policy.

[Carlton Gibson]

There's not consensus to change the policy on the mailing list, so we can push forward with this.

[Tim Graham <timograham@…>]

In 7e6b214:

Fixed #30116 -- Dropped support for Python 3.5.

[Mariusz Felisiak <felisiak.mariusz@…>]

In b711eafd:

Refs #30116 -- Removed unnecessary str() calls in CommonPasswordValidator.

open() and gzip.open() supports path-like objects since Python 3.6.

[Mariusz Felisiak <felisiak.mariusz@…>]

In e0e88cea:

Refs #30116 -- Simplified stdout/stderr decoding with subprocess.run()'s encoding argument.

The encoding argument has been available since Python 3.6.
​https://docs.python.org/3/library/subprocess.html#subprocess.run

[Mariusz Felisiak <felisiak.mariusz@…>]

In d6aff369:

Refs #30116 -- Simplified regex match group access with Match.getitem().

The method has been available since Python 3.6. The shorter syntax is
also marginally faster.