Tests from `tox.ini` are not picked up until it's reopened

[The-Compiler]

With #10 merged, when I e.g. close the "Extension Develop Host" with tox.ini still open, and then start debugging again, tests are not picked up:

I need to close and reopen the file to make things work.

@starlord-daniel could you perhaps take a look? I couldn't find out where the culprit is.