CI: check .xml structure drift against doc-en #2

	# https://docs.github.com/en/actions
	# Checks that the block skeleton of the .xml files changed in a PR stays a mirror
	# of doc-en. Each file is compared to doc-en at the revision it declares to mirror
	# (EN-Revision), so a lagging file does not raise a false positive. The script
	# emits its own ::error annotations.

	name: "Structure"

	on:
	pull_request:
	branches: ["master"]
	types: [opened, synchronize]

	permissions:
	contents: read

	jobs:
	structure:
	name: "Check XML"
	runs-on: ubuntu-22.04
	steps:
	- name: "Checkout translation"
	uses: actions/checkout@v4
	with:
	fetch-depth: 0

	- name: "Checkout php/doc-en"
	uses: actions/checkout@v4
	with:
	path: en
	repository: php/doc-en
	fetch-depth: 0

	- name: "Check structure"
	run: \|
	BASE="${{ github.event.pull_request.base.sha }}"
	git fetch --no-tags --depth=1 origin "$BASE"
	git diff --name-only "$BASE"...HEAD -- '*.xml' \
	\| php8.1 .github/scripts/check-structure.php

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