Set alpha even when current color channels didn’t change #1884

	name: WeasyPrint's tests
	on: [push, pull_request]

	jobs:
	tests:
	name: ${{ matrix.os }} - ${{ matrix.python-version }}
	runs-on: ${{ matrix.os }}
	strategy:
	matrix:
	os: [ubuntu-latest, macos-latest, windows-latest]
	python-version: ['3.13']
	include:
	- os: ubuntu-latest
	python-version: '3.9'
	- os: ubuntu-latest
	python-version: 'pypy-3.9'
	steps:
	- uses: actions/checkout@v4
	- uses: actions/setup-python@v5
	with:
	python-version: ${{ matrix.python-version }}
	- name: Install DejaVu and Ghostscript (Ubuntu)
	if: matrix.os == 'ubuntu-latest'
	run: sudo apt-get update -y && sudo apt-get install fonts-dejavu ghostscript -y
	- name: Install DejaVu, Pango and Ghostscript (MacOS)
	if: matrix.os == 'macos-latest'
	run: \|
	brew update
	brew install --cask font-dejavu
	brew install pango ghostscript
	- name: Install DejaVu, Pango and Ghostscript (Windows)
	if: matrix.os == 'windows-latest'
	run: \|
	C:\msys64\usr\bin\bash -lc 'pacman -S mingw-w64-x86_64-ttf-dejavu mingw-w64-x86_64-pango mingw-w64-x86_64-ghostscript --noconfirm'
	xcopy "C:\msys64\mingw64\share\fonts\TTF" "C:\Users\runneradmin\.fonts" /e /i
	echo "C:\msys64\mingw64\bin" \| Out-File -FilePath $env:GITHUB_PATH
	rm C:\msys64\mingw64\bin\python.exe
	- name: Upgrade pip and setuptools
	run: python -m pip install --upgrade pip setuptools
	- name: Install tests’ requirements
	run: python -m pip install .[test] pytest-xdist
	- name: Launch tests
	run: python -m pytest -n auto
	env:
	DYLD_FALLBACK_LIBRARY_PATH: /opt/homebrew/lib
	- name: Check coding style
	run: python -m ruff check

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