ci: twine check before upload, non-interactive

twine check validates the built artifacts' metadata (long_description
rendering, required fields) so a broken render hits CI logs instead of
landing on PyPI as a malformed project page.

--non-interactive guards against a wedged prompt hanging the pipeline
if the runner ever loses its ~/.pypirc auth.

.gitlab-ci.yml

@@ -21,4 +21,5 @@ pypi-twine:
     - pip install --upgrade pip
     - pip install twine
     - python3 setup.py sdist bdist_wheel
-    - twine upload dist/*
+    - twine check dist/*
+    - twine upload --non-interactive dist/*