ci: bump actions/checkout@v6

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

.github/workflows/test.yml

@@ -11,12 +11,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout pkgcheck-action
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
       with:
         path: pkgcheck-action
 
     - name: Checkout GURU repository
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
       with:
         repository: gentoo/guru
         path: guru