Upgrade GitHub Actions

.github/workflows/docs.yml

@@ -7,11 +7,11 b' jobs:'
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
-    - name: Set up Python 3.8
-      uses: actions/setup-python@v2
+    - uses: actions/checkout@v3
+    - name: Set up Python
+      uses: actions/setup-python@v4
       with:
-        python-version: 3.8
+        python-version: 3.x
     - name: Install Graphviz
       run: |
         sudo apt-get update