Wmul-rivendell

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Extracted the logic for loading and initial filters of the Rivendell Cart Data Dump from FilterCartReportForMusicSchedule. That logic is now in LoadCartDataDump. This refactoring will allow DatabaseStatistics to re-use the code.

Add support for Python 3.12 and 3.13, remove support for Python 3.6 and 3.7

Change the way the trailing comma is added. Python 3.13 doesn't allow a comma to be included in the line terminator. Instead, a dummy additional field is added to the end of the record.

Remove the functionality for fixing the header bug from 3.6.4-3.6.6. It was a niche problem that is no longer relevant and fixing it creates other problems.

Add DatabaseStatistics for generating statistical information about the music database.

Add two additional failure checks to RivendellAudioImporter. One checks for a file with no group (in the root folder). The second checks to see if rdimport could not open the file.

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BugFix on FilterCartReportForMusicScheduler
The new _remove_excluded_groups was not being called correctly.

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RivendellAudioImporter: Catch crashes that occur when renaming a bad file and
the file is locked by another user.

FilterCartReportForMusicScheduler: Add ability to exclude cuts by group name.

cli - load_current_log_line: Make the mail_username and mail_password optional,
even when using the mail function.

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Convert to pyproject.toml and publish to PyPI, vastly simplifying the
installation process.

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Added --fix_header to FilterCartReport to allow for a bug in Rivendell 3.6.4-3.6.6

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Improve crash handling in import_with_file_system_metadata when the problem is a network burp.