Add six to dependencies for publish (#234)

.github/workflows/publish.yml

@@ -21,7 +21,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install setuptools wheel twine
+        pip install setuptools wheel twine six
     - name: Generate SBOM
       run: |
         pip install cyclonedx-bom