Upgrade actions/checkout from v5 to v6

Author: twsl

project/.github/workflows/release.yaml.jinja

@@ -74,7 +74,7 @@ jobs:
     needs: release
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Download artifacts
         uses: actions/download-artifact@v6