Log Message:
databases/ruby-sequel: update to 5.13.0

=== 5.13.0 (2018-10-01)

* Support :single_value type in prepared statements (rintaun) (#1547)

* Make Model.all in static_cache plugin accept a block (AlexWayfer, jeremyevans) \ 
(#1543)

* Add constant_sql_override extension for overriding SQL used for constants such \ 
as CURRENT_TIMESTAMP (celsworth) (#1538)

* Do not cache from_self datasets if options are given (jeremyevans)