Update Node.js version to 20 in deploy workflow

Signed-off-by: Trade Control <admin@tradecontrol.co.uk>

Author: TradeControl

.github/workflows/deploy.yml

@@ -29,6 +29,8 @@ jobs:
       - name: Install, build, and upload your site output
         uses: withastro/action@v4
 
+        with:
+          node-version: 20
         # with:
             # path: . # The root location of your Astro project inside the repository. (optional)
             # node-version: 16 # The specific version of Node that should be used to build your site. Defaults to 16. (optional)