repo_managament/*:
Remove the obsolete
`convert._transform_package_desc_to_output_package()` (the functionality
is now covered by pydantic models directly).
Change all relevant methods to be async.
Change file open commands to make use of aiofiles.

tests/*:
Remove tests for the obsolete
`convert._transform_package_desc_to_output_package()`.
Change all tests for async methods to test using pytest-asyncio.