Add z permissions option to compose mounts to accommodate SELinux hosts

[sarayourfriend]

Description

Hosts using SELinux (ex. RHEL based Linux distros like Fedora) need the z option added to bind mounts to configure file permissions for SELinux docker, otherwise things fail on file permissions issues inside the containers. More information about this is here: https://docs.docker.com/storage/bind-mounts/#configure-the-selinux-label

While it's dangerous to indiscriminately use this, because we scope all bind mounts to the repository, it is perfectly safe to add z to all bind mounts. Folks running SELinux will be conscientious enough to check this. As precedent, pre-commit also sets z by default for docker and docker_image hooks.

Fix

Add z to all bind mounts in docker-compose.yml.

Additional context

I've been working around this by adding it temporarily locally and then removing it. The labels only need to be set once, so this has been manageable for the most part, but any time new files are added, I run into the issue again. Having it added in the compose file would make it so I and others using SELinux don't need to hack around this and remember what to do every time we get a confounding file permissions error locally.