Fix token for TestPyPI (#20)

Author: gahjelle

.github/workflows/publish.yaml

@@ -32,7 +32,7 @@ jobs:
       uses: pypa/gh-action-pypi-publish@release/v1
       with:
         user: __token__
-        password: ${{ secrets.PYPI_API_TOKEN }}
+        password: ${{ secrets.TESTPYPI_API_TOKEN }}
         repository-url: https://test.pypi.org/legacy/
 
     - name: Create GitHub Release