Add GitLab CI/CD for release

.gitignore

 **.pyc
 **/__pycache__
+
+# pypi package builds
+dist/**

.gitlab-ci.yml

+# vim: ts=2
+
+pypi-release:
+  rules:
+    - if: '$CI_COMMIT_TAG =~ /^v\d+/'
+  script:
+    - pip3 install --upgrade pip build twine check-manifest
+    - rm -f dist/*
+    - python3 -m check_manifest
+    - python3 -m build
+    - python3 -m twine check dist/*
+    - TWINE_USERNAME=${PYPI_USER} TWINE_PASSWORD=${PYPI_PASSWORD} python3 -m twine upload --skip-existing --non-interactive dist/*
+

MANIFEST.in

+exclude MANIFEST.in
+exclude poetry.lock
+exclude .gitlab-ci.yml