[gha] poetry -> sphinx-build

.github/workflows/sphinx.yaml

@@ -47,8 +47,8 @@ jobs:
       - name: Render Quarto File
         run: quarto render README.qmd --to rst && mv README.rst docs/index.rst
 
-      - name: Build HTML using Poetry
-        run: poetry run -C docs sphinx-build -M html docs/source/ docs/build/
+      - name: Build HTML using Sphinx
+        run: cd docs && sphinx-build -M html docs/source/ docs/build/
 
       # Upload
       - name: Upload artifacts