Update nokogiri, nokogiri-diff, rdoc, drop support for Ruby < 3 #151

	name: CI
	on: [push, pull_request]

	env:
	JRUBY_OPTS: -Xcext.enabled=true

	jobs:
	build:
	name: "Test / Ruby ${{ matrix.ruby }}"
	runs-on: ubuntu-latest
	strategy:
	matrix:
	ruby:
	- "3.0"
	- "3.1"
	- "3.2"
	- "3.3"
	fail-fast: false

	steps:
	- name: Checkout
	uses: actions/checkout@v2
	with:
	fetch-depth: 10

	- uses: ruby/setup-ruby@v1
	with:
	ruby-version: ${{ matrix.ruby }}
	bundler-cache: true

	- uses: actions/setup-python@v2
	with:
	# This should match lib/github/markups.rb GitHub::Markups::MARKUP_RST
	python-version: '3.x'

	- uses: actions/cache@v2
	with:
	path: ~/.cache/pip
	key: ${{ runner.os }}-pip

	- name: Install Perl dependencies
	run: \|
	curl -1sLf \
	'https://dl.cloudsmith.io/public/nxadm-pkgs/rakudo-pkg/setup.deb.sh' \
	\| sudo -E bash
	sudo apt-get update -qq
	sudo apt-get install perl rakudo-pkg

	curl -L http://cpanmin.us \| perl - --sudo App::cpanminus
	sudo cpanm --installdeps --notest Pod::Simple

	- name: Install Python dependencies
	run: python -m pip install docutils

	- name: Run rake
	run: \|
	export PATH=$PATH:/.perl6/bin:/opt/rakudo-pkg/bin
	bundle exec rake

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