[Ignore] Update Notebook dts (PowerShell#2862)

Co-authored-by: TylerLeonhardt <TylerLeonhardt@users.noreply.github.com>

Author: github-actions[bot]

vscode.proposed.d.ts

@@ -567,6 +567,7 @@ declare module 'vscode' {
 
 export const onDidOpenNotebookDocument: Event<NotebookDocument>;
 export const onDidCloseNotebookDocument: Event<NotebookDocument>;
+export const onDidSaveNotebookDocument: Event<NotebookDocument>;
 
 /**
  * All currently known notebook documents.