Add datasets folder to wheel

[romanlutz]

Description

Adding the datasets folder to the wheel because it otherwise causes issues when users don't provide a dataset and use the default (as it's not part of the wheel but expected to be present).

Note that it isn't inside the pyrit package directory, so the installation puts it into a directory at the same level as pyrit like another python package which is not great and could cause confusion and conflicts. We should absolutely address this in a future release, but it'll unblock the next one.

Tests

• no new tests required
• new tests added
• existing tests adjusted

Documentation

• no documentation changes needed
• documentation added or edited
• example notebook added or updated