Remove unused import

lib/core/configuration.dart

@@ -2,7 +2,6 @@ import 'dart:convert';
 import 'dart:io' as io;
 import 'dart:typed_data';
 
-import 'package:collection/collection.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'package:flutter_sodium/flutter_sodium.dart';