Backports from anyio (old main) branch to main branch

[ianthomas23]

Backports cherry-picked from anyio (old main) branch to main branch:

• Fixed error accessing sys.stdout/sys.stderr when those are None #1247
• Detect parent change in more cases on unix #1271
• Remove some potential dead-code. #1273
• Try to add workflow to publish nightlies #1276
• remove deprecated ipyparallel methods now that they are broken anyway #1282
• Add 20 min timeout dowstream ipyparallel #1287
• Suggest to make implementations of some function always return awaitable #1295
• Use supported_features=['debugger'] in kernel info reply #1296
• make debugger class configurable #1307
• Fix test_print_to_correct_cell_from_child_thread #1312
• Remove implicit bind_kernel in %qtconsole #1315
• Copy payloadpage.page from IPython #1317
• Remove downstream_check #1318
• Remove link to numfocus for funding. #1320
• Try to force precommit-ci to send autoupdate PRs. #1325
• Some formatting changes to prepare bumping ruff pre-commit. #1329
• minor code reformating valid ruff 0.9.6 #1330
• Ignore or fix most of the remaining ruff 0.9.6 errors #1331
• Remove dead code. #1332
• Refine deprecation error messages. #1334
• Check ignores warnings are still relevant. #1340
• Enable ruff G002 and fix 6 occurences #1341
• Remove unused ignores lints. #1342
• Try to debug non-closed iopub socket #1345
• Make our own mock kernel methods async #1346
• Try to reenable tests from downstream ipywidgets #1350
• Remove deprecated modules since 4.3 (2016). #1352
• TQDM workaround due to unresponsive maintainer #1363
• Fix OutStream using _fid before being defined #1373
• chore: update pre-commit hooks #1388

Separate commit to bumpy mypy to the latest 1.16.1, reusing some of #1333.

[ianthomas23]

The CI failures are:

• Low coverage that I need to improve.
• A flaky test in qtconsole.

I am going to merge as is, and we'll see if this improves the overnight ipython downstream tests.