CI: Add test coverage

.gitlab-ci.yml

@@ -15,6 +15,7 @@ run-tests:
     - pip3 install -I git+https://dev.gajim.org/gajim/python-nbxmpp.git@master
     - pip3 install -I pylint==2.4.4
     - pip3 install -I codespell
+    - pip3 install -I coverage
     - pip3 install -I css-parser
     - pip3 install -I keyring
     - pip3 install -I packaging
@@ -23,10 +24,16 @@ run-tests:
     - mypy -V
     - mypy gajim
     - scripts/dev/pylint-ci.sh --jobs=2 gajim
-    - python3 -m unittest discover -s test/no_gui -v
+    - coverage run --source=gajim -m unittest discover -s test/no_gui -v
+    - coverage report -mi
+    - coverage xml -i
     - codespell -I codespell.conf --skip="*__pycache__*,gajim/data/icons,gajim/data/sounds,gajim/data/emoticons" gajim
     - deactivate
     - rm -rf civenv-master
+  coverage: "/TOTAL.+ ([0-9]{1,3}%)/"
+  artifacts:
+    reports:
+      cobertura: coverage.xml
 
 run-appdata:
   stage: test