Update deprecated actions/cache to v4

Author: gilch

.github/workflows/test-package.yml

@@ -20,7 +20,7 @@ jobs:
       with:
         python-version: 3.10.15
     - name: Cache pip
-      uses: actions/cache@v1
+      uses: actions/cache@v4
       with:
         path: ~/.cache/pip
         key: ${{ runner.os }}-pip-${{ hashFiles('requirements-dev.txt') }}