chore(ng9): scroll test mock ignore new typing

Author: damyanpetev

projects/igniteui-angular/src/lib/directives/scroll-inertia/scroll_inertia.directive.spec.ts

@@ -311,7 +311,7 @@ describe('Scroll Inertia Directive ', () => {
                 return {
                     addPointer: (arg) => {}
                 };
-            };
+            } as any;
         }