Update poetry.lock

[rhine3]

I have run into this issue a few times: ipython/ipykernel#540 and I believe John Kearney (?) has as well. It's a minor but annoying issue.

We can solve it either by downgrading ipython to version 7.10 or eventually upgrading ipykernel to 6.0 (but this version is not released yet; latest release was 5.5 on May 13).

This will also change several dependencies as well as perform some automatic updates via Poetry. So, I don't want to do this before the 0.5 release, just in case the changed packages create bugs that testing doesn't catch.

[rhine3]

Ended up having to update this anyway to get poetry-built environment to pip install. Some dependency issues were causing poetry to select a version of scikit-learn that failed to install. This was fixed by using poetry to upgrade to scikit-learn 0.24.2.