Bump tensorboard to 2.21.0, setuptools to 83.0.0

[dxqb]

Summary

tensorboard 2.21.0 no longer imports the pkg_resources API removed in setuptools 82, so the setuptools<82 constraint added in #1305 is no longer needed. setuptools stays pinned like everything else in requirements-global.txt, just moved to the current 83.0.0.

The pip/setuptools bootstrap in lib.include.sh and update.bat pinned setuptools to 81.0.0 to stay under that constraint; both are bumped to 83.0.0 so the bootstrap installs the intended version directly.

Fixes #1307.

probably waiting on #1244 to not cause any more unnecessary conflicts, or might even be obsolete after #1244?
@hameerabbasi

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[hameerabbasi]

Yeah; I think the latest TensorBoard doesn't take setuptools as a dep, so we can remove it completely; and it will be obsolete after #1244 since the lockfile does the pinning for transitive deps; we should only pin top-level ones.

[hameerabbasi]

See 03251e2.

[dxqb]

conflicts with torch:
❯ The conflict is caused by:
The user requested setuptools==83.0.0
torch 2.12.0+cu130 depends on setuptools<82
torch 2.12.0+cu130 depends on setuptools<82

cannot be merged before torch 2.13:

⎿  torch 2.12.0: ['setuptools<82']
torch 2.12.1: ['setuptools<82']
torch 2.13.0: ['setuptools>=77.0.3']

@hameerabbasi sorry, can you undo in pixi too, please

[hameerabbasi]

conflicts with torch: ❯ The conflict is caused by: The user requested setuptools==83.0.0 torch 2.12.0+cu130 depends on setuptools<82 torch 2.12.0+cu130 depends on setuptools<82

cannot be merged before torch 2.13:

⎿ torch 2.12.0: ['setuptools<82'] torch 2.12.1: ['setuptools<82'] torch 2.13.0: ['setuptools>=77.0.3']

@hameerabbasi sorry, can you undo in pixi too, please

I just removed the dep completely -- and pixi auto-locked it to 81.x. It hard-errors early if there's a resolution failure. So there's no real need to undo.