🚀 chore: Grant write permissions to demo workflow

The demo workflow now has write permissions to the repository's contents, enabling it to update the GitHub Pages deployment.

Author: tarampampam

.github/workflows/demo.yml

@@ -19,6 +19,8 @@ jobs:
   demo:
     name: Generate files and update the demo (GitHub Pages)
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
     steps:
       - uses: actions/checkout@v4
       - name: Run this action