use autoload for file so that explict requires are not required

Author: lsylvester

lib/active_storage/postgresql.rb

@@ -2,6 +2,9 @@
 
 module ActiveStorage
   module PostgreSQL
-    # Your code goes here...
+    extend ActiveSupport::Autoload
+
+    autoload :File, "active_storage/postgresql/file"
+
   end
 end

lib/active_storage/service/postgresql_service.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'active_storage/postgresql/file'
-
 module ActiveStorage
   # Wraps a PostgreSQL database as an Active Storage service. See ActiveStorage::Service for the generic API
   # documentation that applies to all services.