remove _fetch_dataset

[jsosulski]

MNE removed _fetch_dataset completely on the main branch. I simply replaced usage of _fetch_file with retrieve from pooch as done in other locations of the code.

[sylvchev]

There is a flake8 error that blocks the CI, could you correct it?

[jsosulski]

I saw that as well and found it strange. On my local machine running flake8 moabb does not produce any errors and looking at the files that cause the errors, I did not even change them.

[sylvchev]

Yes, I found the error. It could be corrected easily, but I do not understand why this is raised by the CI just now. The code is in the codebase for quite some times.

[sylvchev]

The linting error is now correct, we could rebase, re-run the tests and merge !

[jsosulski]

Thanks for the rebase and merge!