Hello!

The staging branch has been accumulating updates for a while now.
We have Mesa 19, Sphinx 2.0, GStreamer 1.16, ALSA 1.1.9, as well as some
Python updates.  See `git shortlog -n master..staging` for the scoop.

I suggest we "freeze" (meaning no further updates, only bugfixes) this
branch tomorrow at midnight UTC, and then merge it once the CI lights
are green.

Anything missing before the freeze?