Update pages.yml

Author: mtessmer

.github/workflows/pages.yml

@@ -15,7 +15,7 @@ jobs:
       uses: actions/setup-python@v1
       with:
         python-version: 3.9
-    - uses: actions/cache@v2
+    - uses: actions/cache@v4
       with:
         path: |
           ~/.cache/pip