ci: modify docs job to build documentation using Sphinx

Author: threeal

.github/workflows/build.yml

@@ -105,11 +105,8 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v3.5.3
 
-      - name: Configure project
-        uses: threeal/cmake-action@v1.2.0
-        with:
-          source-dir: ${{ matrix.package }}
-          options: BUILD_DOCS=ON
+      - name: Install dependencies
+        run: pip3 install -r docs/requirements.txt
 
       - name: Build documentation
-        run: cmake --build ${{ matrix.package }}/build --target docs
+        run: sphinx-build -b html docs build/docs -W --keep-going