Drop Python 3.6

[alex]

It's no longer supported by upstream. We've been warning (though not committing to a deadling) for a while. Usage is currently around 7% or so. Our expectation is that by the time Ubuntu 18.04 goes EOL (April 2023), we should be able to drop it. Expected timeline:

• 39.0 -- deprecated
• 40.0 -- final warning
• 41.0
  • Drop support: Remove from CI, update python-requires, remove any branches
  • Remove python_version >= "3.7" from CI constraints
  • Migrate from setup.cfg to pyproject.toml completely #8116
  • Upgrade to pyo3 0.18 #6935
  • pyo3 upgrade follow-ups

[alex]

cc: @glyph @mattsb42-aws @bmw @ohemorange @bitprophet @mhils for our various high-profile down-streams

[glyph]

Thanks for the heads up. We're all set: twisted/twisted#10303

[bitprophet]

I'm only just now dropping <=3.5 on most of my crap, but once the dust settles there (it includes also dropping py2) I'll take a closer look at whether my installbase would get pissy on dropping 3.6 too 🤔

[reaperhulk]

3.6 represents a shade under 7% of downloads now, but we've run into quite a few CI issues as a last-mover on dropping 3.6. 40.0.0 will still be the final release that supports 3.6.

[bitprophet]

On my end, I just checked, and while Paramiko is ~10-15% 3.6 (in 3rd place after 3.7 and 3.8), fabric and its alias fabric2 are both easily 50-60% 3.6 still. Huh. (And while it doesn't typically require cryptography installation, Invoke is also 50-60% 3.6.)