Update .gitlab-ci.yml file

.gitlab-ci.yml

-stages:
-  - deploy
-
-before_script:
-   - pip install twine
-   - python setup.py sdist
-
-deploy_production:
-  stage: deploy
-  variables:
-    TWINE_USERNAME: $PRODUCTION_USERNAME
-    TWINE_PASSWORD: $PRODUCTION_PASSWORD
-  script:
-    - twine upload dist/* --verbose