bump actions/cache@v5

Node.js 20 actions are deprecated.

See-also: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/
Signed-off-by: Florian Albrechtskirchinger <falbrechtskirchinger@gmail.com>
Signed-off-by: Arthur Zamarin <arthurzam@gentoo.org>

Author: falbrechtskirchinger

action.yml

@@ -9,7 +9,7 @@ runs:
   using: composite
   steps:
     - name: Cache pkgcheck
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: |
           ~/.cache/pkgcore