Log Message:
databases/ruby-sequel: update to 5.15.0

=== 5.15.0 (2018-12-01)

* Add :conn_str option in the postgres adapter for PostgreSQL connection \ 
strings, if the pg driver is used (graywolf) (#1572)

* Add :qualify_tables option to class_table_inheritance plugin to automatically \ 
qualify subclass tables with superclass qualifier (benalavi) (#1571)

* Access already allocated connections in a thread safe manner when checking out \ 
connections in the sharded threaded connection pool (jeremyevans)

* Automatically support datasets using qualified tables in the \ 
class_table_inheritance plugin without having to use the :alias option \ 
(benalavi) (#1565)

* Support rename_column without emulation on SQLite 3.25+ (jeremyevans)

* Do not remove currently cached many_to_one associated objects when changing \ 
the related foreign key value from nil to non-nil (jeremyevans)

* Do not validate new *_to_many associated objects twice when saving in the \ 
nested_attributes plugin (jeremyevans)

* Add Model#skip_validation_on_next_save! for skipping validation on next save \ 
call (jeremyevans)