GabrielBB/xvfb-action is no longer maintained and points to
coactions/setup-xvfb. The switch should eliminate this warning in CI
builds:
Node.js 12 actions are deprecated. Please update the following actions
to use Node.js 16: GabrielBB/xvfb-action@v1.6. For more information see:
https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.
Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>