Merge remote-tracking branch 'origin/release'

Merge branch 'barry/2024-07-08/minor-plex-docs/release' into 'release'

Build PETSc and petsc4py docs with the same requirements file

See merge request petsc/petsc!7678

Update sphinx packages used to build docs make petsc4py docs shared common requirements.txt

This prevents errors such as below when building docs

Running Sphinx v7.3.7
Using PETSC inventory from fi

Update sphinx packages used to build docs make petsc4py docs shared common requirements.txt

This prevents errors such as below when building docs

Running Sphinx v7.3.7
Using PETSC inventory from file:///Users/barrysmith/Src/petsc/doc/_build/html/objects.inv
<Inventory (url): PETSc v3.21, 7842 objects>

Exception occurred:
File "petsc4py/PETSc.pyx", line 1, in init petsc4py.PETSc
ValueError: numpy.dtype size changed, may indicate binary incompatibility. Expected 96 from C header, got 88 from PyObject

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Merge branch 'eijkhout/fix-script-python' into 'main'

Script: Update python in petscnagupgrade.py

See merge request petsc/petsc!7299

Remove duplicates and switch to python3

Merge branch 'barry/2024-01-03/docs-c2html' into 'main'

Remove recursive build of c2html files; no longer uses classic makefiles

See merge request petsc/petsc!7167

Remove recursive build of c2html files; no longer uses classic makefiles

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