types: use globalThis instead of global for NativeDate

Fix for issue Automattic#14988 
The global is defined in the @types/node package, which is not in the dependencies.
Without the package, NativeDate would be interpreted as any by typescript, and resolves the types in the Schema incorrectly.

Author: Bl4sio

types/index.d.ts

@@ -25,7 +25,7 @@
 /// <reference path="./virtuals.d.ts" />
 /// <reference path="./augmentations.d.ts" />
 
-declare class NativeDate extends global.Date { }
+declare class NativeDate extends globalThis.Date { }
 
 declare module 'mongoose' {
   import Kareem = require('kareem');