CI enhancements

.gitlab-ci.yml

@@ -18,11 +18,18 @@ backend-tests:
     DB_HOST: postgres
     DB_PORT: 5432
 
+    # Pip cache
+    PIP_CACHE_DIR: "$CI_PROJECT_DIR/.cache/pip"
+
+  cache:
+    paths:
+      - .cache/pip
+
   before_script:
     - apk --update add build-base
     - pip install -r tests-requirements.txt codecov
 
   script:
     - python setup.py test
-    - flake8
     - codecov
+    - flake8