Update user-defined-types/exercise.md #71

	# Based on https://securitylab.github.com/research/github-actions-preventing-pwn-requests/
	name: Generate Course Schedule

	on:
	pull_request:
	paths:
	- "src/**.md"

	jobs:
	build:
	runs-on: ubuntu-latest

	steps:
	- name: Checkout
	uses: actions/checkout@v4

	- name: Setup Rust cache
	uses: ./.github/workflows/setup-rust-cache

	- name: Generate Schedule
	run: \|
	mkdir -p ./course-schedule
	cargo run -p mdbook-course --bin course-schedule > course-schedule/schedule

	# GitHub does not provide a reliable way to determine the PR number from which
	# a workflow_run was triggered (https://github.com/orgs/community/discussions/25220),
	# so we'll do the slightly awkward thing and put that in the artifact. This means
	# schedules could potentially be spammed to any PR in the repository, but that is
	# not an awful outcome (and clear, reportable evidence of abuse).
	echo ${{ github.event.number }} > ./course-schedule/pr-number

	- uses: actions/upload-artifact@v4
	with:
	name: course-schedule
	path: course-schedule/

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