Update build.yml

Author: jamesmstone

.github/workflows/build.yml

@@ -82,6 +82,7 @@ jobs:
         VERCEL_TOKEN: ${{ secrets.VERCEL_TOKEN }}
       run: |-
         cd main
+        datasette install datasette-publish-vercel
         wget https://latest.datasette.io/fixtures.db
         datasette publish vercel tils.db fixtures.db \
           --token $VERCEL_TOKEN \