Mostly they're updated to the latest. I've held back on two packages:

- pyparsing: the exception messages have changed, and not always in a
  good way (they're less intelligible); that was breaking unit tests for
  the errors.
- aiomonitor: the new version has an HTTP console, but I'm not sure what
  the implications of that are when run under katsdpcontroller.
  I've opened NGC-1179 to deal with that.

There are a few code changes needed to deal with the upgrades (mostly to
deal with deprecation warnings):

- pytest-asyncio no longer wants you to override the `event_loop`
  fixture. See
  [here](https://pytest-asyncio.readthedocs.io/en/latest/how-to-guides/index.html)
  for it's recommended replacements.
- xarray warns that Dataset.dims should be replaced by Dataset.sizes
- signal.py was using a 1D array with 1 element as if it was a scalar.
  numpy is now warning about that. The type annotation has also been
  fixed.

This makes them match better to requirements.txt and friend. I'm hoping
the update to pip-tools might also fix a weird glitch where sometimes it
reports coverage as being a dependency of itself.

pytest-asyncio 0.23 changed the way event loops work and caused a number
of issues, including pytest-dev/asyncio#705 and
pytest-dev/pytest-asyncio#718. I wasn't able to find an easy way around
these for the qualification test, so for now I've pinned pytest-asyncio
to <0.22 (the 0.22 release was a half-way point to 0.23 and has been
yanked).