Sphinx warning in docs for config value jupyterlite_dir has type str, defaults to PosixPath

[matthewfeickert]

Following Issue #2297, the test build of the docs is failing with

WARNING: The config value `jupyterlite_dir' has type `str', defaults to `PosixPath'.

This warning is treated as an error as we do this intentionally

pyhf/docs/Makefile

Lines 5 to 8 in b687487

	# W: Turn warnings into errors
	# n: Run in nit-picky mode
	SPHINXOPTS = -W --keep-going #-n
	SPHINXBUILD = sphinx-build

I'm not sure if this means that we need to update

pyhf/docs/conf.py

Lines 531 to 532 in b687487

	# JupyterLite configuration
	jupyterlite_dir = "lite"

to be a Pathlib Path or not. I'm not sure how that would work though.