Add CD/CI for testing

.gitlab-ci.yml

@@ -0,0 +1,18 @@
+before_script:
+  - python -m venv venv
+  - source venv/bin/activate
+  - pip install --editable ./[dev]
+
+test:
+  parallel:
+    matrix:
+      - PY_IMAGE:
+        - python:latest
+        - python:3.10-slim
+        - python:3.11-slim
+  image: $PY_IMAGE
+  coverage: /^TOTAL.*? ([0-9]+\.[0-9]+%)$/
+  script:
+    - py.test --cov --cov-report=term
+    - black --check ./d2warehouse
+    - flake8 ./d2warehouse