Add deploy stage and publish job to CI/CD pipeline

The commit adds a new deployment stage and a publish job to the .gitlab-ci.yml file. The deploy stage is placed after the test stage, and the publish job is defined to run only on tags. The publish job installs Hatchling, Twine, and Build packages, builds the project, and uploads the distribution files to PyPI using the provided token as the password.

.gitlab-ci.yml

@@ -2,6 +2,7 @@ image: python:3.10
 
 stages:
   - test
+  - deploy
 
 before_script:
   - python -V
@@ -9,10 +10,20 @@ before_script:
   - source venv/bin/activate
   - pip install -U pip
   - pip install .
-  - echo "[KeyDelivery]" > config.ini
-  - echo "key = ${API_KEY}" >> config.ini
-  - echo "secret = ${API_SECRET}" >> config.ini
 
 test:
   stage: test
-  script: python -m unittest test.py
+  script: 
+  - echo "[KeyDelivery]" > config.ini
+  - echo "key = ${API_KEY}" >> config.ini
+  - echo "secret = ${API_SECRET}" >> config.ini
+  - python -m unittest test.py
+
+publish:
+  stage: publish
+  script:
+    - pip install -U hatchling twine build
+    - python -m build .
+    - python -m twine upload --username __token__ --password ${PYPI_TOKEN} dist/*
+  only:
+    - tags