Digiarch

Better exception handling & bug fixes

* Now running an SQLite based backend
* The CLI has been spring cleaned, as it suffered from functionality bloat

Updates datamodels dependency to use acamodels from PyPI instead.

This release could not be uploaded to PyPI. See Release 0.7.1 instead.
* New custom signatures implemented. This includes Lotus 1-2-3 Spreadsheets and Markup Word/Excel files.
* File extension fix command added.
* `--all` option added, which runs all commands in digiarch in order
* Internal data classes have been moved to Pydantic data models, cf. https://github.com/aarhusstadsarkiv/datamodels

digiarch` now leverages the multiprocessing functionality of `siegfried` to significantly increase identification performance.

Checksums are now calculated using SHA256 instead of BLAKE2.
Fixed minor issues with identify & checksum multiprocessing and subprocessing.