Add `read_ixmp4()` method and extend integration test #1287

	# This workflow installs the package and builds the docs
	# For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions

	name: build the docs

	on:
	push:
	branches: [ 'main' ]
	pull_request:
	branches: [ '**' ]

	jobs:
	docs:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4

	- name: Set up Python
	uses: actions/setup-python@v5
	with:
	python-version: '3.10'

	- name: Install Pandoc
	uses: r-lib/actions/setup-pandoc@v1

	- name: Install dependencies and package for building the docs
	run: pip install -e .[tutorials,optional_plotting,docs]

	- name: Build the docs
	run: make --directory=docs html

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