Fix lints from dart pub publish (#177)

diff --git a/packages/file/lib/src/forwarding/forwarding_random_access_file.dart b/packages/file/lib/src/forwarding/forwarding_random_access_file.dart
index 4d193f0..2b5a8d6 100644
--- a/packages/file/lib/src/forwarding/forwarding_random_access_file.dart
+++ b/packages/file/lib/src/forwarding/forwarding_random_access_file.dart
@@ -2,7 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart=2.10
 import 'dart:convert';
 import 'dart:typed_data';
 
diff --git a/packages/file/pubspec.yaml b/packages/file/pubspec.yaml
index d5c9987..2498dd1 100644
--- a/packages/file/pubspec.yaml
+++ b/packages/file/pubspec.yaml
@@ -10,6 +10,7 @@
   sdk: '>=2.12.0-0 <3.0.0'
 
 dependencies:
+  meta: ^1.3.0
   path: ^1.8.0
 
 dev_dependencies: