meta: add a manual deploy for website (#4171)

Because the GHA bot is merging the release PR, the website workflow
doesn't run automatically. By adding a manual dispatch, we can make sure
the website is updated after each release.

.github/workflows/website.yml

@@ -7,6 +7,7 @@ on:
       - yarn.lock
       - 'website/**'
       - '.github/workflows/website.yml'
+  workflow_dispatch:
 
 jobs:
   deploy: