PyPI install incorrectly ships a `tests` package

[asumagic]

Describe the bug

If you check the .whl file of SB 1.0, for instance, you will notice that there is an empty tests/ (with only the __init__.py). This is not a huge deal, but it has the unintended consequence that the user now has a tests package at their root level.

Expected behaviour

That package should not exist on normal or editable installs.

To Reproduce

import tests

$ cat env/lib/python3.xx/speechbrain-xxx.dist-info/top_level.txt 
speechbrain
tests

Environment Details

No response

Relevant Log Output

No response

Additional Context

This is probably due to the way packages are specified in the setup.py.

Does not seem like it would be linked to #2484 but it's worth investigating anyway.