fix: upgrade actions/cache v4→v5 and upload-artifact v4→v7 (Node 24)

Node.js 20 actions are deprecated — GitHub will force Node.js 24
starting June 2, 2026.

- actions/cache/restore v4 → v5
- actions/cache/save v4 → v5
- actions/upload-artifact v4.6.2 → v7

Using version tags for clarity.

See: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

action.yml

@@ -81,7 +81,7 @@ runs:
 
     - id: load-cache
       if: ${{ env.CACHE_KEY }}
-      uses: actions/cache/restore@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+      uses: actions/cache/restore@v5
       with:
         path: ~/cache-apt-pkgs
         key: cache-apt-pkgs_${{ env.CACHE_KEY }}
@@ -110,14 +110,14 @@ runs:
 
     - id: upload-logs
       if: ${{ env.CACHE_KEY && inputs.debug == 'true' }}
-      uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+      uses: actions/upload-artifact@v7
       with:
         name: cache-apt-pkgs-logs_${{ env.CACHE_KEY }}
         path: ~/cache-apt-pkgs/*.log
 
     - id: save-cache
       if: ${{ env.CACHE_KEY && ! steps.load-cache.outputs.cache-hit }}
-      uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+      uses: actions/cache/save@v5
       with:
         path: ~/cache-apt-pkgs
         key: ${{ steps.load-cache.outputs.cache-primary-key }}