ci: use twine instead of plugin

.drone.yml

@@ -10,12 +10,14 @@ steps:
   - python -m pip install build
   - python -m build
 - name: publish
-  image: plugins/pypi
-  settings:
-    setupfile: setup.cfg
-    username:
+  image: python
+  commands:
+  - python -m pip install twine
+  - python -m twine upload -u $USERNAME -p $PASSWORD dist/*
+  environment:
+    USERNAME:
       from_secret:  pypi_username
-    password:
+    PASSWORD:
       from_secret: pypi_password
 trigger:
   event: