.github: add octave packages for testbench

process_test requires octave. Before running octave,
signal and io pakcages should be loaded.

Signed-off-by: Fred Oh <fred.oh@linux.intel.com>

.github/workflows/pull-request.yml

@@ -109,6 +109,7 @@ jobs:
       - name: apt get
         run: sudo apt-get update &&
              sudo apt-get -y install valgrind alsa-utils libasound2-dev
+             octave octave-io octave-signal
 
       # testbench needs some topologies.
       - name: build test topologies