Colab broken by version skew

[vaclavhanzl]

Colab is broken. Please consider my PR #432 which makes it work again.

Colab now fails with module 'numpy' has no attribute 'object' because the depricated np.object now throws error, not just warning as before. This is fixed in the main branch however it does not work with the current Colab code either. My PR fixes it by using the latest commit from the pl_upgrades branch which uses new versions suitable for the current Colab environment.

In the longer term we likely first want the pl_upgrades branch merged to main and then maybe we want something from the current multimer-colab-patch branch (the commit used so far is the top of this branch). But the Colab is a very ephemeral thing anyway (standing on the ever changing Colab environment) so I would do whatever works for the moment (e.g. my PR now).