Update deploy_docs workflow to use Python 3.8 and modern GitHub Actions

Co-authored-by: wannaphong <8536487+wannaphong@users.noreply.github.com>

Author: Copilot

.github/workflows/deploy_docs.yml

@@ -9,11 +9,11 @@ jobs:
     name: Build
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
-    - name: Set up Python 3.7
-      uses: actions/setup-python@v1
+    - uses: actions/checkout@v4
+    - name: Set up Python 3.8
+      uses: actions/setup-python@v5
       with:
-        python-version: 3.7
+        python-version: 3.8
     - name: Install dependencies
       run: |
         sudo apt install pandoc