Make sphinx workflow work with python 3.8 but conda version of 3.12

.github/workflows/sphinx-docs.yml

@@ -10,7 +10,17 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-python@v4
         with:
-          python-version: "3.12.4"
+          python-version: "3.8"
+      - name: Set-up miniconda for macos and ubuntu
+        uses: conda-incubator/setup-miniconda@v2
+        with:
+          auto-update-conda: true
+          python-version: 3.12
+          miniconda-version: "latest"
+      - name: Create conda env
+        run: conda create -n NCP python=3.12
+      - name: Install pip
+        run: conda run -n NCP conda install pip
       - name: Install dependencies
         run: |
           pip install -r requirements.txt