ci: move to Node 24 versions of checkout, upload-artifact and action-gh-release

actions/checkout@v4, actions/upload-artifact@v4 and
softprops/action-gh-release@v2 still target Node.js 20, which the runners
now force onto Node.js 24 with a deprecation warning. Their current majors
(checkout v7, upload-artifact v7, action-gh-release v3) run on Node.js 24.

.github/workflows/aur.yml

@@ -45,7 +45,7 @@ jobs:
         run: pacman -Syu --noconfirm --needed git openssh pacman-contrib
 
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
         with:
           # The updated recipes are committed back to main, not to the tag.
           ref: main