Remove unused import from file_io_stub_test.dart

Co-authored-by: santoshvandari <63558580+santoshvandari@users.noreply.github.com>

Author: Copilot

test/src/file_io_stub_test.dart

@@ -1,4 +1,3 @@
-import 'dart:typed_data';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:docx_viewer/src/file_io_stub.dart';