[@types/slate-plain-serializer] Add delimiter option (#40992)
[@types/slate-plain-serializer] Add delimiter option (#40992)

* Add delimiter option to slate-plain-serializer

* Fix semicolon separator

* Removed patch version

markogresak/DefinitelyTyped,dsebastien/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped