change sphinx version to support sphinx-book-theme #6

	name: Build and publish documentation

	on:
	push:
	branches:
	- main
	pull_request:

	jobs:
	build:
	runs-on: ubuntu-latest
	strategy:
	fail-fast: false
	steps:
	- name: Set up Pandoc
	uses: r-lib/actions/setup-pandoc@v2

	- name: Checkout source
	uses: actions/checkout@v2
	with:
	fetch-depth: 0

	- name: Set up Python
	uses: actions/setup-python@v3
	with:
	python-version: "3.10"

	- name: Install filterjax and all its dependencies
	run: \|
	conda install pip
	pip install .
	pip install .[dev]

	- name: Checkout gh-pages
	uses: actions/checkout@v2
	with:
	ref: gh-pages
	path: docs/_build/html

	- name: Build docs
	if: github.ref == 'refs/heads/main' \|\| startsWith(github.ref, 'refs/tags')
	run: \|
	sphinx-build docs docs/_build/html
	touch docs/_build/html/.nojekyll

	- name: Publish docs to gh-pages
	# Only once from main or a tag
	if: github.ref == 'refs/heads/main' \|\| startsWith(github.ref, 'refs/tags')
	# We pin to the SHA, not the tag, for security reasons.
	# https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/security-hardening-for-github-actions#using-third-party-actions
	uses: peaceiris/actions-gh-pages@bbdfb200618d235585ad98e965f4aafc39b4c501 # v3.7.3
	with:
	github_token: ${{ secrets.GITHUB_TOKEN }}
	publish_dir: docs/_build/html
	keep_files: true

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