feat: automatic testing

This commit adds a .gitlab-ci.yml file, which is responsible for
defining jobs to be run (in this case only running the test suite)

ref: N25B-65

test/unit/test_temp.py

@@ -0,0 +1,6 @@
+"""
+Temporary file to demonstrate unit testing.
+"""
+
+def test_temp():
+    assert True