CI: use pipx run for publish task

* we were still trying to install python packages via pip install here

.gitlab-ci.yml

@@ -39,9 +39,8 @@ 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=${PYPI_PASSWORD} python3 -m twine upload --skip-existing --non-interactive dist/*
+    - pipx run check-manifest
+    - pipx run build
+    - pipx run twine check dist/*
+    - TWINE_USERNAME=${PYPI_USER} TWINE_PASSWORD=${PYPI_PASSWORD} pipx run twine upload --skip-existing --non-interactive dist/*