Grant preview-website job the permissions Firebase deploy needs

Signed-off-by: Tamal Saha <tamal@appscode.com>

Author: tamalsaha

.github/workflows/preview-website.yml

@@ -15,6 +15,10 @@ jobs:
   build:
     name: Build
     runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+      checks: write
+      pull-requests: write
     steps:
       - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
         with: