Authentication error when trying to upload PYPI package

Question

I have this:

python -m twine upload dist/* -u __token__ -p $PYPI_TOKEN

in my publish.yml. On push this is run. However, I get an error in the CI:

ERROR    HTTPError: 403 Forbidden from https://test.pypi.org/legacy/            
         Invalid or non-existent authentication information. See                
         https://test.pypi.org/help/#invalid-auth for more information. 

When clicking on it I see that "Ensure that the username you are using is __token__." is probably the issue. Where is this variable supposed to be set and how?