ICU-21107 Update ICU4C minimum standard version from C++11 to C++17 #1

	# Copyright (C) 2016 and later: Unicode, Inc. and others.
	# License & terms of use: http://www.unicode.org/copyright.html
	#
	# GitHub Action configuration script for ICU continuous integration tasks.

	name: GHA ICU Docs

	on:
	push:
	branches:
	- main
	- 'maint/maint*'
	paths:
	- 'docs/**'
	pull_request:
	branches: '**'
	paths:
	- 'docs/**'
	workflow_dispatch:
	# To trigger the Env Test workflow manually, follow the instructions in
	# https://docs.github.com/en/actions/managing-workflow-runs/manually-running-a-workflow

	permissions:
	contents: read

	jobs:
	# Build job
	# Keep in sync with deploy workflow in `jekyll-gh-pages.yml`
	test-docs-build:
	name: Test build of User Guide docs
	runs-on: ubuntu-latest
	steps:
	- name: Checkout
	uses: actions/checkout@v3
	- name: Setup Ruby
	uses: ruby/setup-ruby@v1
	with:
	ruby-version: '2.7.4' # Not needed with a .ruby-version file
	bundler-cache: true # runs 'bundle install' and caches installed gems automatically
	cache-version: 0 # Increment this number if you need to re-download cached gems
	- name: Setup Pages
	id: pages
	uses: actions/configure-pages@v3
	with:
	generator_config_file: docs/_config.yml
	- name: Build with Jekyll
	# Outputs to the './_site' directory by default
	run: \|
	cd docs # root directory of markdown, also contains Jekyll configs, etc.
	bundle install
	# The baseurl arg is parsed from the `baseurl` field of _config.yml.
	bundle exec jekyll build --baseurl "${{ steps.pages.outputs.base_path }}"
	env:
	JEKYLL_ENV: production

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