Use GNU_FORMAT in tarfile to avoid '././@PaxHeader' in archives

[ehaupt]

Summary

This merge request updates the archive_files function to use the GNU_FORMAT when creating tar archives. The current tar file creation process leads to the inclusion of unwanted '././@PaxHeader' directories in the tarballs. These directories are empty and serve no purpose in our context, potentially causing confusion and issues with tarball consumers.

Problem

When archiving files using the default tar format, the Python tarfile library adds PaxHeader directories to store extended header information. This behavior, while compliant with POSIX standards, is unnecessary for our use case and results in additional, unneeded directories in our archives.

Solution

By setting the format parameter of the tarfile.open method to tarfile.GNU_FORMAT, we force the use of the GNU tar format. This format does not use PaxHeader directories to store extended headers, thus preventing their creation. This change leads to the generation of cleaner archives, avoiding the inclusion of these empty directories.

Impact

This change will make our tar archives simpler and potentially more compatible with systems that do not handle the PaxHeader directories properly. It will ensure that only the necessary files are included in the archives, without additional metadata directories.

Testing

The change has been tested by creating archives with various sets of files and examining the contents of the resulting tarballs. No PaxHeader directories were included in any of the tested archives, confirming that the change achieves its intended effect.

[chezou]

@ehaupt Thanks for the patch! I'll release a new version.