Fix coverage measurement

We were not omitting setup.py, the test sources
or the 3rd part libraries in .venv

Author: dmerejkowsky

.coveragerc

@@ -0,0 +1,8 @@
+[run]
+source = tsrc
+
+omit =
+  cli_ui/tests/*
+  .venv/*
+
+branch = True

ci.sh

@@ -4,5 +4,5 @@ set -e
 which black && black --check .
 mypy cli_ui
 pyflakes cli_ui/__init__.py cli_ui/tests/test_cli_ui.py
-pytest --cov . --cov-report term
+pytest --cov cli_ui --cov-report term
 sphinx-build -W docs docs/_build/html