Cast env to symbol, fixes deprecation warning

Warning:

  DEPRECATION WARNING: Passing a string to ActiveRecord::Base.establish_connection for a configuration lookup is deprecated, please pass a symbol (:development) instead.

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -78,7 +78,7 @@ def create_current(environment = env)
         each_current_configuration(environment) { |configuration|
           create configuration
         }
-        ActiveRecord::Base.establish_connection environment
+        ActiveRecord::Base.establish_connection(environment.to_sym)
       end
 
       def drop(*arguments)