correct optional dep for publishing on PyPi

[sylvchev]

Could not publish on PyPi:

HTTP Error 400: Invalid value for requires_dist. Error: Can't have direct dependency: 'tdlda @ git+https://github.com/jsosulski/[email protected] ; extra == "external"'

PyPi does not support non-package dependencies and url as package, as it is the case here for tdlda

[sylvchev]

It is not possible to put tdlda in dev dependency as an extra : see python-poetry/poetry#759. Dependency groups will be available in poetry 1.2.0 : python-poetry/poetry#1644

Meanwhile, I put tdlda in dev and updated all Github Actions to install only main dep in test and main+dev in docs. Checking everything on a local server, I corrected two errors in unit tests when datasets are already downloaded