Update CI matrix to use 3.4.0-preview2; update README #242

	# This workflow uses actions that are not certified by GitHub.
	# They are provided by a third-party and are governed by
	# separate terms of service, privacy policy, and support
	# documentation.
	# This workflow will download a prebuilt Ruby version, install dependencies and run tests with Rake
	# For more information see: https://github.com/marketplace/actions/setup-ruby-jruby-and-truffleruby

	name: CI

	on: [push, pull_request]

	jobs:
	test:
	strategy:
	fail-fast: false
	matrix:
	ruby: ['3.0', 3.1, 3.2, 3.3, '3.4.0-preview2']
	activerecord: [6.1, '7.0', 7.1, 7.2, '8.0']
	exclude:
	- ruby: '3.0'
	activerecord: 7.2
	- ruby: '3.0'
	activerecord: '8.0'
	- ruby: '3.1'
	activerecord: '8.0'
	- ruby: '3.4.0-preview2'
	activerecord: 6.1
	- ruby: '3.4.0-preview2'
	activerecord: '7.0'

	runs-on: ubuntu-latest

	name: Test against Ruby ${{ matrix.ruby }} / ActiveModel ${{ matrix.activerecord }}

	steps:
	- uses: actions/checkout@v4
	- name: Set up Ruby
	uses: ruby/setup-ruby@v1
	with:
	ruby-version: ${{ matrix.ruby }}
	- name: Install dependencies
	env:
	ACTIVE_RECORD_VERSION: ~> ${{ matrix.activerecord }}.0
	run: bundle install --jobs 4 --retry 3
	- name: Run specs
	env:
	ACTIVE_RECORD_VERSION: ~> ${{ matrix.activerecord }}.0
	run: bundle exec rspec spec --backtrace

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