Update .gitlab-ci.yml to include versioneer vendor install

Added a step to install versioneer with the `--vendor` flag in the CI pipeline. This ensures versioneer is properly set up for managing versioning during builds. The change helps streamline the build and deployment process.

.gitlab-ci.yml

@@ -5,5 +5,6 @@ run-default:
     - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
   script:
     - pip install build twine versioneer
+    - versioneer install --vendor
     - python -m build
     - TWINE_PASSWORD=${CI_JOB_TOKEN} TWINE_USERNAME=gitlab-ci-token python -m twine upload --repository-url ${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/pypi dist/*