Updates to sphinx.yml

Add step to install dependencies from requirements.txt

Author: mg-andrews

.github/workflows/sphinx.yml

@@ -11,6 +11,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
+    - name: Install dependencies
+      run: pip install -r requirements.txt
     - name: Build HTML
       uses: ammaraskar/sphinx-action@master
     - name: Upload artifacts