Add CI/CD pipeline to build and deploy package

This adds CI/CD capabilities to the project. It behaves consistently with the outline in #20 where the pipeline will trigger on pushes to main and tagged commits. A new release version is produced for a tagged commit whereas a new development version is pushed for any commit to main.

The prod branch will need to be updated manually for now until a fix is found for updating it automatically. See here for more detail.

.gitlab-ci.yml

+default:
+  image: python:3.12
+
+
+variables:
+  PIP_CACHE_DIR: "$CI_PROJECT_DIR/.cache/pip"
+  PIP_INDEX_URL: "https://__token__:${CI_JOB_TOKEN}@gitlab.com/api/v4/projects/$CI_PROJECT_ID/packages/pypi/simple"
+  PIP_EXTRA_INDEX_URL: "https://pypi.org/simple"
+  REPO_URL: "${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/pypi"
+  PACKAGE_NAME: "rc-gpfs"
+
+stages:
+  - release
+  - cleanup
+
+release:
+  stage: release
+  only:
+    - main
+    - tags
+  before_script:
+    - python3 --version ; python3 -m pip --version  # For debugging
+    - pip install --upgrade pip
+    - pip install poetry
+    - poetry self add "poetry-dynamic-versioning[plugin]"
+    - poetry install
+  script:
+    - export POETRY_DYNAMIC_VERSIONING_DEBUG=1
+    - export VERSION=$(poetry version -s)  # Get version from poetry
+    - echo "Creating release for version $VERSION"
+    - poetry config repositories.gitlab ${REPO_URL}
+    - poetry publish --username gitlab-ci-token --password ${CI_JOB_TOKEN} --repository gitlab --build
+
+cleanup_old_packages:
+  stage: cleanup
+  script:
+    - echo "Fetching package versions..."
+    - |
+      PACKAGE_VERSIONS=$(curl --header "PRIVATE-TOKEN: $CI_JOB_TOKEN" "https://gitlab.com/api/v4/projects/${CI_PROJECT_ID}/packages?package_name=${PACKAGE_NAME}" | jq -r '.[].version')
+      echo "All versions: $PACKAGE_VERSIONS"
+    - |
+      VERSIONS_TO_DELETE=$(echo "$PACKAGE_VERSIONS" | sort -r | tail -n +3)
+      echo "Versions to delete: $VERSIONS_TO_DELETE"
+    - |
+      for VERSION in $VERSIONS_TO_DELETE; do
+        echo "Deleting version $VERSION..."
+        curl --request DELETE --header "PRIVATE-TOKEN: $CI_JOB_TOKEN" "${REPO_URL}/${PACKAGE_NAME}/$VERSION"
+      done
+  only:
+    - schedules