update workflow

Author: dholth

.github/workflows/upload-pypi-source.yml

@@ -20,7 +20,7 @@ jobs:
       run: python -c "import sys; print(sys.version)"
     - name: Build
       run: |
-        python -m pip install scons pytoml packaging
+        python -m pip install scons tomli packaging
         scons -c
         scons
         python -m pip install dist/enscons*.whl