Drop python 3.8 support

[mjurbanski-reef]

Description of the Change

Drop Python 3.8 to encourage use of newer syntax and use of newest dependency versions.

Argument for this change:

• Python 3.8 is currently only receives security only patches, and hits complete End of Life in <5months https://devguide.python.org/versions/ .
• we can already see python 3.8 support eating away at devleopment time in PRs like fix: Incompatible type hint #1888, and personally having created a number of PR for bittensor project I have also attest that number of time I had to change my code simply to support python 3.8
• multiple 3rd party packages stopped publishing wheels for python 3.8 already and this trend will only continue.
• seems like most subnets now run on 3.10 or newer. With Python 3.11 delivering a modest performance boost, this trend should be encouraged
• the potentially freed up effort can be redirect to officially support current newest stable Python 3.12 , which has been out for months already but has yet to be declared as officially support by bittensor package

pypistats python_minor bittensor -l
┌──────────┬─────────┬───────────┐
│ category │ percent │ downloads │
├──────────┼─────────┼───────────┤
│ 3.10     │  77.00% │    26,669 │
│ 3.11     │   7.27% │     2,519 │
│ 3.9      │   5.12% │     1,773 │
│ 3.12     │   3.67% │     1,272 │
│ 3.8      │   3.57% │     1,237 │
│ null     │   3.19% │     1,106 │
│ 3.13     │   0.07% │        24 │
│ 3.7      │   0.06% │        21 │
│ 3.6      │   0.03% │        11 │
│ 3.5      │   0.00% │         1 │
│ Total    │         │    34,633 │
└──────────┴─────────┴───────────┘

Date range: 2024-04-01 - 2024-04-30

Alternate Designs

Leave Python 3.8 at the cost of CI and, more importantly, development time.

Possible Drawbacks

The non-actively developed subnets or system will have to update to python 3.9, if they are still stuck

Verification Process

CI

Release Notes

• Drop Python 3.8 support

[gus-opentensor]

@mjurbanski-reef thank you for the PR! We will let the community know prior to getting this out.

[gus-opentensor]

@mjurbanski-reef can you update and I will merge this!

[mjurbanski-reef]

rebased to current staging