Update dependencies pv5.9
A rewrite of !367 (closed) which drops the Python update (for now). It's a bit more hairy, so that's going to be put on hold until the rest of the updates are OK (so that problems in Python can be focused on).
A rewrite of !367 (closed) which drops the Python update (for now). It's a bit more hairy, so that's going to be put on hold until the rest of the updates are OK (so that problems in Python can be focused on).
