try this a different way

.github/workflows/documentation.yml

@@ -18,13 +18,13 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           python-version: 3.x
-      - run: cd mkdocs
       - run: echo "cache_id=$(date --utc '+%V')" >> $GITHUB_ENV 
       - uses: actions/cache@v4
         with:
           key: mkdocs-material-${{ env.cache_id }}
           path: .cache
           restore-keys: |
             mkdocs-material-
+      - working-directory: ./mkdocs
       - run: pip install mkdocs-material 
       - run: mkdocs gh-deploy --force