Fix AUR workflow

[Dacchiii]

Summary

The Arch Linux AUR test workflow was failing for two reasons:

1. The python-pyglet AUR dependency was not installed.
2. The Verify installation step required an X server, but no X server was running in the CI environment.

This PR addresses both issues.

Install AUR dependency

The workflow failed because python-pyglet, which is required by the package being tested, was not installed.

I added an Install AUR dependencies step that creates a dedicated aur-builder user and builds and installs python-pyglet from the AUR.

The dependency is built with makepkg as the aur-builder user:

useradd -m aur-builder
mkdir -p /tmp/aur
chown -R aur-builder:aur-builder /tmp/aur
echo "aur-builder ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
git config --global --add safe.directory "${GITHUB_WORKSPACE}"
su aur-builder -c "git config --global --add safe.directory '${GITHUB_WORKSPACE}'"
cd /tmp/aur
git clone "https://aur.archlinux.org/pyglet.git"
chown -R aur-builder:aur-builder /tmp/aur
cd pyglet
su aur-builder -c "makepkg -si --noconfirm"

Add a virtual X server

The Verify installation step then failed because pyglet attempts to connect to an X display when the application is started, while no X server is available in the CI environment.

I added two steps:

• Install X server installs libxrender and xorg-server-xvfb.
• Start Xvfb starts a virtual X server and sets the DISPLAY environment variable.

The packages are installed with:

sudo pacman -S --noconfirm libxrender xorg-server-xvfb

Xvfb is then started with:

Xvfb :99 -screen 0 1280x1024x24 &
echo "DISPLAY=:99" >> "$GITHUB_ENV"

With these changes, the Verify installation step can successfully run in the CI environment.