Fix newly enforced lint (#57)

diff --git a/test/utils.dart b/test/utils.dart
index 595415a..66f103e 100644
--- a/test/utils.dart
+++ b/test/utils.dart
@@ -2,9 +2,8 @@
 // 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.
 
-import 'package:test/test.dart';
-
 import 'package:pub_semver/pub_semver.dart';
+import 'package:test/test.dart';
 
 /// Some stock example versions to use in tests.
 final v003 = Version.parse('0.0.3');
diff --git a/test/version_constraint_test.dart b/test/version_constraint_test.dart
index c9d8e61..1434cfe 100644
--- a/test/version_constraint_test.dart
+++ b/test/version_constraint_test.dart
@@ -2,9 +2,8 @@
 // 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.
 
-import 'package:test/test.dart';
-
 import 'package:pub_semver/pub_semver.dart';
+import 'package:test/test.dart';
 
 import 'utils.dart';
 
diff --git a/test/version_range_test.dart b/test/version_range_test.dart
index 67c7f35..6e27c3a 100644
--- a/test/version_range_test.dart
+++ b/test/version_range_test.dart
@@ -2,9 +2,8 @@
 // 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.
 
-import 'package:test/test.dart';
-
 import 'package:pub_semver/pub_semver.dart';
+import 'package:test/test.dart';
 
 import 'utils.dart';
 
diff --git a/test/version_union_test.dart b/test/version_union_test.dart
index 89f9a85..857f10e 100644
--- a/test/version_union_test.dart
+++ b/test/version_union_test.dart
@@ -2,9 +2,8 @@
 // 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.
 
-import 'package:test/test.dart';
-
 import 'package:pub_semver/pub_semver.dart';
+import 'package:test/test.dart';
 
 import 'utils.dart';