fix: remove duplicate neon pooler (#990)

## Description

Fixes the issue with Vercel preview deployments failing.

It appears that the old `PGHOST` environment variable injected by neon
was:

`ep-snowy-snowflake-a2vc5pa2.eu-central-1.aws.neon.tech`

It is now:

`ep-snowy-snowflake-a2vc5pa2.eu-central-1-pooler.aws.neon.tech`

Notice the `-pooler` being attached automatically to the `PGHOST`.

## References

> The following changes were made to the [Neon Vercel
Integration](https://vercel.com/integrations/neon):
>
>To ensure that users accessing a Neon database from a serverless
environment have enough connections, the DATABASE_URL and PGHOST
environment variables added to a Vercel project by the Neon integration
are now set to a pooled Neon connection string by default. Pooled
connections support up to 10,000 simultaneous connections. Previously,
these variables were set to an unpooled connection string supporting
fewer concurrent connections.

https://neon.tech/docs/changelog

https://neon.tech/docs/guides/vercel#manage-vercel-environment-variables

turbo.json

@@ -90,6 +90,7 @@
     "FONT_CAVEAT_URI",
     "POSTGRES_URL",
     "DATABASE_URL",
+    "DATABASE_URL_UNPOOLED",
     "POSTGRES_PRISMA_URL",
     "POSTGRES_URL_NON_POOLING",
     "E2E_TEST_AUTHENTICATE_USERNAME",