Update main.yml

.github/workflows/main.yml

@@ -16,7 +16,7 @@ jobs:
 
     - uses: ammaraskar/sphinx-action@master
       with:
-        pre-build-command: "pip install sphinx -U && pip install sphinx_rtd_theme -U"
+        pre-build-command: "python -m pip install --upgrade pip && pip install sphinx -U && pip install sphinx_rtd_theme -U"
         docs-folder: "micropython/docs/"
 
     - uses: actions/upload-artifact@v1