ci: update github action checkout to v4 #19

	---
	# yamllint disable rule:line-length
	name: Test converting README.md to README.html
	on: # yamllint disable-line rule:truthy
	pull_request:
	merge_group:
	branches:
	- main
	types:
	- checks_requested
	push:
	branches:
	- main
	permissions:
	contents: read
	jobs:
	test_converting_readme:
	runs-on: ubuntu-latest
	permissions:
	contents: write
	steps:
	- name: Update pip, git
	run: \|
	set -euxo pipefail
	sudo apt update
	sudo apt install -y git

	- name: Check out code
	uses: actions/checkout@v4

	- name: Remove badges from README.md prior to converting to HTML
	run: sed -i '1,8 {/^\[\!.*actions\/workflows/d}' README.md

	- name: Convert README.md to HTML
	uses: docker://pandoc/core:latest
	with:
	args: >-
	--from gfm --to html5 --toc --shift-heading-level-by=-1
	--template .pandoc_template.html5
	--output README.html README.md

	- name: Upload README.html as an artifact
	uses: actions/upload-artifact@master
	with:
	name: README.html
	path: README.html

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