Merge branch 'ci_update' into 'master'

CI docker image update

See merge request !1032

ci/debian-buster/Dockerfile

@@ -26,11 +26,11 @@ RUN pip3 install --upgrade pip
 RUN pip3 install pylint
 RUN pip3 install pep8
 RUN pip3 install pytest-xdist
-# tests/pytest dependencies
-RUN pip3 install dnspython jinja2 pytest pytest-html pytest-xdist
+# tests/pytest dependencies: skip over broken versions
+RUN pip3 install 'dnspython != 2.0.0' jinja2 'pytest != 6.0.0' pytest-html pytest-xdist
 
-# Wireshark/dumpcap for Deckard
-RUN apt-get install -y -qqq wireshark-common
+# packet capture tools for Deckard
+RUN apt-get install --no-install-suggests --no-install-recommends -y -qqq tcpdump wireshark-common
 
 # Faketime for Deckard
 RUN apt-get install -y -qqq faketime