chore: Bump actions/cache from 4 to 5 (#616)

Author: dependabot[bot]

.github/workflows/checks.yml

@@ -98,7 +98,7 @@ jobs:
       # temporary (rate limiting, network issue, etc.), and we always want to retry those links
       # everytime this action is run.
       - name: Restore lychee cache
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: .lycheecache
           key: cache-lychee-${{ github.sha }}