fix: .env DATABASE_URL postgres host changed from 'localhost' to 'postgres'

.env.example

@@ -8,7 +8,7 @@ DB_NAME=film-db
 DB_PORT=5432
 
 # PRISMA
-DATABASE_URL=postgresql://${DB_USER}:${DB_PASSWORD}@localhost:${DB_PORT}/${DB_NAME}?schema=public
+DATABASE_URL=postgresql://${DB_USER}:${DB_PASSWORD}@postgres:${DB_PORT}/${DB_NAME}?schema=public
 
 # ADMINER
 ADMINER_PORT=8080