update actions

Author: xadupre

.github/workflows/documentation.yml

@@ -35,7 +35,7 @@ jobs:
         run: python -m pip install -r requirements-dev.txt
 
       - name: Cache pip
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: ~/.cache/pip
           key: ${{ runner.os }}-pip-${{ hashFiles('requirements-dev.txt') }}