feat: Adds `vega-themes.json` using `vl_convert` #2986

	name: lint

	on: [push, pull_request]

	jobs:
	build:
	runs-on: ubuntu-latest
	name: ruff-mypy
	steps:
	- uses: actions/checkout@v4
	- name: Set up Python 3.12
	uses: actions/setup-python@v5
	with:
	python-version: "3.12"
	# Installing all dependencies and not just the linters as mypy needs them for type checking
	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	pip install hatch
	- name: Lint with ruff
	run: \|
	hatch run ruff check .
	- name: Check formatting with ruff
	run: \|
	hatch run ruff format --diff .
	hatch run ruff format --check .
	- name: Lint with mypy
	run: \|
	hatch run mypy altair tests

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