Hardcode 20 for pool

Author: dorner

config/database.yml

@@ -5,7 +5,7 @@ default: &default
   database: diaper_dev
   username: <%= ENV.fetch("PG_USERNAME", 'postgres') %>
   password: <%= ENV.fetch("PG_PASSWORD", nil) %>
-  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
+  pool: 20
   timeout: 5000
 
 development: &development