Update vega #159

	name: Backend CI workflow

	on:
	push:
	paths:
	- chartlets.py/**
	branches:
	- main
	pull_request:
	paths:
	- chartlets.py/**

	jobs:
	python-tests:
	runs-on: ubuntu-latest
	strategy:
	fail-fast: false
	matrix:
	python-version: ["3.10", "3.11", "3.12", "3.13"]
	defaults:
	run:
	working-directory: chartlets.py

	steps:
	- uses: actions/checkout@v3

	- name: Set up Python ${{ matrix.python-version }}
	uses: actions/setup-python@v3
	with:
	python-version: ${{ matrix.python-version }}

	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	pip install .[dev,demo]

	- name: Lint with flake8
	run: \|
	# stop the build if there are Python syntax errors or undefined names
	flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
	# exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
	flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics

	- name: Run unit tests
	shell: bash -l {0}
	run: \|
	pytest --cov=chartlets --cov-report=xml

	- name: Upload coverage reports to Codecov
	uses: codecov/codecov-action@v4
	with:
	fail_ci_if_error: true
	directory: chartlets.py/
	flags: backend
	verbose: true
	token: ${{ secrets.CODECOV_TOKEN }}

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