Change branch to main in CI

.gitlab-ci.yml

@@ -26,7 +26,7 @@ pypi_publish:
   before_script:
    - pip install twine
   only:
-   - master
+   - main
   stage: publish
   when: on_success
   script:

tox.ini

 [tox]
 envlist = python3.9
+skipsdist = True
 
 [testenv]
 deps = pytest