Add a slide on the rule of zero #144

	name: Publish LaTeX slides
	on:
	push:
	paths:
	- 'talk/**'
	branches:
	- master

	jobs:
	publish-slides:
	runs-on: ubuntu-latest
	strategy:
	matrix:
	version: [ essentials, full ]
	steps:
	- uses: actions/checkout@v3
	- name: Setup essentials course
	if: matrix.version == 'essentials'
	run: echo '\basictrue' > talk/onlybasics.tex
	- name: Compile LaTeX document
	uses: xu-cheng/latex-action@v2
	with:
	root_file: C++Course.tex
	latexmk_use_xelatex: true
	args: -f -pdf -interaction=nonstopmode -shell-escape
	working_directory: talk
	extra_system_packages: "py-pygments"
	- name: Commit to download repository
	run: \|
	set -x
	git clone -b download https://${GITHUB_ACTOR}:${{secrets.GITHUB_TOKEN}}@github.com/${{github.repository}}.git download
	cd download
	mkdir -p talk
	cp ../talk/C++Course.pdf "talk/C++Course_${{ matrix.version }}.pdf"
	git config --global user.name 'github-actions[bot]'
	git config --global user.email 'github-actions[bot]@users.noreply.github.com'
	git add -f "talk/C++Course_${{ matrix.version }}.pdf"
	if (git diff --quiet) \|\| (git diff --staged --quiet)
	then
	git commit --amend -m "Update C++Course.pdf"
	until git push --force-with-lease origin download; do
	git pull --rebase origin download
	done
	else
	echo "No changes to commit"
	fi
	git push

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