databases/ruby-sequel: update to 5.50.0

=== 5.50.0 (2021-11-01)

* Make Migrator :allow_missing_migration_files also allow down migrations
  where the current database version is greater than the last migration file
  version (francisconeves97) (#1789)

* Fix Model#freeze in composition, serialization, and
  serialization_modification_detection plugins to return self (jeremyevans)
  (#1788)

* Fix typecasting of lazy columns when using lazy_attributes plugin in model
  where dataset selects from subquery (jeremyevans)

* Add :before_preconnect Database option, for configuring extensions loaded
  via :preconnect_extensions (MarcPer, jeremyevans) (#1786)

* Change Dataset#columns! to use a LIMIT 0 query instead of a LIMIT 1 query
  (jeremyevans)

* Add sql_log_normalizer extension for normalizing logged SQL, helpful for
  analytics and sensitive data (jeremyevans)

* Add support for range_merge, multirange, and unnest, and PGMultiRange#op
  to pg_range_ops extension (jeremyevans)

* Add pg_multirange extension with support for PostgreSQL 14+ multirange
  types (jeremyevans)

=== 5.49.0 (2021-10-01)

* Switch block_given? usage to defined?(yield) (jeremyevans)

* Support table aliases for JOIN USING columns on PostgreSQL 14+
  (jeremyevans)

* Support calling PostgreSQL procedures without arguments (jeremyevans)

* Support hstore subscripts in pg_hstore_ops on PostgreSQL 14+, for updating
  only part of an hstore value (jeremyevans)

* Support JSONB subscripts in pg_json_ops on PostgreSQL 14+, for updating
  only part of a JSONB value (jeremyevans)

* Support SQL::Expression#sequel_ast_transform for custom AST transforms on
  arbitrary expressions (jeremyevans)

* Add Database#create_trigger :replace option on PostgreSQL 14+ for CREATE
  OR REPLACE TRIGGER (jeremyevans)

* Make auto_validations plugin automatically setup no_null_byte validations
  (jeremyevans)

* Add Model#validates_no_null_byte to validation_helpers plugin
  (jeremyevans)

(taca)