chore(ci): bump GitHub Actions to Node.js 24-compatible versions

Bumps actions across all template and repo workflows to avoid the
Node.js 20 deprecation (enforced June 2026):
- actions/checkout v3/v4 → v6
- actions/cache v4 → v5
- actions/setup-go v5 → v6
- actions/setup-python v4/v5 → v6
- peter-evans/create-pull-request v5/v6 → v7

templates/dev-portfolio/.github/workflows/deploy.yml

@@ -26,7 +26,7 @@ jobs:
       deploy-host: ${{ steps.check.outputs.host }}
     steps:
     - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
       with:
         sparse-checkout: hugoblox.yaml
         sparse-checkout-cone-mode: false