FIX: Typo

.gitlab-ci.yml

@@ -61,7 +61,7 @@ unittest_py3.8:
   image: python:3.8
   script: &python_test_script
     - touch ~/.pycaosdb.ini
-    - pip install nose pytest pytest-cov pytest-dateutil jsonschema==4.0.1
+    - pip install nose pytest pytest-cov python-dateutil jsonschema==4.0.1
     - pip install .
     - python -m pytest unittests