remove dependency on Six
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 63ad16d..5fadc27 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -483,7 +483,7 @@
 
       - name: Python setup
         run: |
-          python -m pip install --upgrade pip setuptools wheel flake8 six tornado twisted zope.interface
+          python -m pip install --upgrade pip setuptools wheel flake8 tornado twisted zope.interface
           python --version
           pip --version