CI: Install python3-build & add --break-system-packages for Localstripe

[H--o-l]

GitHub is rolling out ubuntu-24.04 as the new ubuntu-latest on GitHub
Actions¹. Previously it was ubuntu-22.04.

There are many small breaking changes that people are complaining about in
this update².

Localstripe is impacted by the fact that pip now fails on installing a paquet
system-wide with the following error:

error: externally-managed-environment

× This environment is externally managed
╰─> To install Python packages system-wide, try apt install
    python3-xyz, where xyz is the package you are trying to
    install.

    If you wish to install a non-Debian-packaged Python package,
    create a virtual environment using python3 -m venv path/to/venv.
    Then use path/to/venv/bin/python and path/to/venv/bin/pip. Make
    sure you have python3-full installed.

    If you wish to install a non-Debian packaged Python application,
    it may be easiest to use pipx install xyz, which will manage a
    virtual environment for you. Make sure you have pipx installed.

    See /usr/share/doc/python3.12/README.venv for more information.

There are multiple solutions to this as proposed in the error message:

• Use sudo apt install python3-...
• Use a venv with python -m venv venv
• Use a venv with pipx
• Use the pip option --break-system-packages
• Use ubuntu-22.04 instead of ubuntu-latest

For the package build, python3-build exists, so let's use it. For
localstripe-*.tar.gz, as we already are in an isolated container where
breaking Python is meaningless, and as there is nothing in that container that
might actually break when we install Localstripe, let's just use the option
--break-system-packages.

After this commit, the CI works again with ubuntu-latest.

Footnotes

1. https://github.blog/changelog/2024-09-25-actions-new-images-and-ubuntu-latest-changes/ ↩

2. https://github.com/actions/runner-images/issues/10636 ↩

[adrienverge]

Thanks for fixing this! Among the various solutions, this one is simple and efficient. We can always switch to another in the future.

[adrienverge]

Is sudo really needed? I'm wondering whether this container is already run as root.

[H--o-l]

I tested without and the error message said that I wasn't root, so it's required sadly.

[H--o-l]

the exact error message:

Run apt install python3-build

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

E: Could not open lock file /var/lib/dpkg/lock-frontend - open (13: Permission denied)
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?
Error: Process completed with exit code 100.