File dependency conflict

[akadatsky]

We have an issue with latest version of Flutter:

import 'dart:io';
import 'package:flutter_cache_manager/flutter_cache_manager.dart';

flutter_cache_manager overrides dart:io, cause in flutter_cache_manager declared:
export 'package:file/file.dart' show File;

Look at this for details:
Baseflow/flutter_cache_manager#320

This could be fixed by:

import 'package:flutter_cache_manager/flutter_cache_manager.dart' as fcm;

  Future<void> loadNetworkPDF() async {
    final fetchedFile =
        await fcm.DefaultCacheManager().getSingleFile(widget.networkURL!);
    await (writeCounter(fetchedFile.readAsBytesSync()));
    path = (await _localFile).path;
  }

Could you please fix it?

[ksokolovskyi]

@akadatsky Check this PR, it is working.
#34