Fix typo in `@uppy/core` types (#3230)

Co-authored-by: lucatrazzi <luca.trazzi@garaio.com>

packages/@uppy/core/types/index.d.ts

@@ -194,7 +194,7 @@ export interface ErrorResponse {
 }
 
 export interface SuccessResponse {
-  uploadUrl?: string
+  uploadURL?: string
   status?: number
   body?: any,
   bytesUploaded?: number