Add initial support for Python 3.15

[DanielNoord]

Before we can consider #2462 we first need to support 3.15 to begin with.

This:

• Bumps stdlibs to the latest version to get py315 support
• Adds the 3.15 marker where needed in tox and CI files
• Ignores tests/integration/test_hypothesmith.py on 3.15 as libcst doesn't support it (yet)
• Unignores the django integration test
• Adds version specifiers to some imports that do not support 3.15 yet
• Adds the 3.15 marker to metadata
• Ignores an issue in pygments
• Updates the lock file

Quite a lot of changes, but all necessary to make 3.15 pass on CI in its fullest capacity.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.15%. Comparing base (2fb94e1) to head (80b86e0).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2466   +/-   ##
=======================================
  Coverage   99.15%   99.15%           
=======================================
  Files          40       41    +1     
  Lines        3067     3068    +1     
  Branches      665      665           
=======================================
+ Hits         3041     3042    +1     
  Misses         14       14           
  Partials       12       12           

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[DanielNoord]

@staticdev Do you think you can give this as review?

[staticdev]

Sure @DanielNoord i am on vacation but will be back in 9 days.

[staticdev]

@DanielNoord I would not rush for this one, actually I was thinking of finally remove support for Python 2 first, since 3.15 is pre-release still we don't need to merge this now, but we can keep it here.

[DanielNoord]

@staticdev I think adding support for lazy imports might be quite a lot of work. See the linked issue, as we'll also need to coordinate a bit with ruff and others.

Merging this will at least unblock this as we'll be able to start testing and parsing the lazy imports.

I think it would be good for the community if isort supports lazy imports from day 1.

[staticdev]

Fine @DanielNoord, I checked the PR and I think also can be a preliminary implementation then. Since it is updating dependencies, it needs to have a new uv.lock.