See if we can build packages on Gitlab CI

.gitlab-ci.yml

+image: python:3.11
+
+variables:
+  PIP_CACHE_DIR: "$CI_PROJECT_DIR/.cache/pip"
+
+cache:
+  paths:
+    - .cache/pip
+
+before_script:
+  - python --version ; pip --version  # For debugging
+  - python -m venv venv
+  - source venv/bin/activate
+
+test:
+  script:
+    - pip install build auditwheel abi3audit pytest
+    - python -m build
+    - auditwheel repair dist/*.whl
+    - abi3audit -vs wheelhouse/*.whl
+    - pip install wheelhouse/*.whl
+    - pytest
+  artifacts:
+    paths:
+      - dist/*.tar.gz
+      - wheelhouse/*