Update KeyPoint.d.ts

Update wrong parameter for KeyPoint typings. Keypoint.point is undefined.
KeyPoint.pt is the correct param

Author: headsho111

lib/typings/KeyPoint.d.ts

@@ -1,7 +1,7 @@
 import { Point2 } from './Point2.d';
 
 export class KeyPoint {
-  readonly point: Point2;
+  readonly pt: Point2;
   readonly size: number;
   readonly angle: number;
   readonly response: number;