Workflows: Update to cache/actions@v4

Author: pc-coholic

.github/workflows/tests.yml

@@ -20,7 +20,7 @@ jobs:
         uses: actions/setup-python@v1
         with:
           python-version: 3.11
-      - uses: actions/cache@v1
+      - uses: actions/cache@v4
         with:
           path: ~/.cache/pip
           key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}