Update dependencies to more recent versions

[bmerry]

Mostly they're updated to the latest. I've held back on a few 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.
• pytest-asyncio: it deprecates the way we override the event loop (either its type in the unit tests, or its fixture scope in qualification), and the replacement doesn't work properly (More difficulties in 0.23 with async fixtures pytest-dev/pytest-asyncio#718). I've pinned it to <0.22 until we can sort that out, and opened NGC-1181.

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

• 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.

Checklist (if not applicable, edit to add (N/A) and mark as done):

• If dependencies are added/removed: update setup.cfg and .pre-commit-config.yaml
• (N/A) If modules are added/removed: use sphinx-apidoc -efo doc/ src/ to update files in doc/
• Ensure copyright notices are present and up-to-date
• (N/A) If qualification tests are changed: attach a sample qualification report
• (N/A) If design has changed: ensure documentation is up to date
• (N/A) If ICD-defined sensors have been added: update fake_servers.py in katsdpcontroller to match