chore(ci) bump actions/cache@v4

Author: fffonion

.github/workflows/tests.yml

@@ -113,7 +113,7 @@ jobs:
       uses: actions/checkout@v2
 
     - name: Setup cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: |
           /home/runner/work/cache