Update gitlab-ci pipewire to version 0.3.31

Updating PipeWire to the latest version lets us check that everything
still works well, and shows users that they are able to use it.

[daniels: Updated to 0.3.31, use symbolic ref tags rather than SHAs.
          0.3.32 is released, but doesn't build in our Debian
          environment; this is fixed upstream but there is no release
	  for it yet.]

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>