Add DATABASE_TYPE environment variable

Determines which Prisma schema to use

docker-compose.yml

@@ -7,6 +7,7 @@ services:
       - "3000:3000"
     environment:
       DATABASE_URL: postgresql://umami:umami@db:5432/umami
+      DATABASE_TYPE: postgresql
       HASH_SALT: replace-me-with-a-random-string
     depends_on:
       - db