Update actions/cache action to v6

.github/workflows/matrix.yml

@@ -29,7 +29,7 @@ jobs:
         uses: actions/checkout@v7
 
       - name: Restore prek cache
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         with:
           path: var/prek
           key: arch-prek-v1-${{ hashFiles('.pre-commit-config.yaml') }}