Changes

debian-trixie-build: add tshark

This is needed for running pysim unit tests on generic nodes.
As of now we're executing them on the 'simtester' node, which cannot
run more than one job at once, making build verification for large
pysim patchsets extremely slow.

Change-Id: Idbe934e5cc29b06fd1b13b85893de5856eca836e
Related: osmo-ci.git I986d88545f64e13cd571ba9ff56bc924822e39a0