fix lint (#76)

* Fix newly enforced lint

* pubspec and CI cleanup
diff --git a/.github/workflows/test-package.yml b/.github/workflows/test-package.yml
index 0a2a874..8c20eeb 100644
--- a/.github/workflows/test-package.yml
+++ b/.github/workflows/test-package.yml
@@ -23,7 +23,7 @@
         sdk: [dev]
     steps:
       - uses: actions/checkout@v2
-      - uses: dart-lang/setup-dart@v0.3
+      - uses: dart-lang/setup-dart@v1.0
         with:
           sdk: ${{ matrix.sdk }}
       - id: install
@@ -50,7 +50,7 @@
         sdk: [dev]
     steps:
       - uses: actions/checkout@v2
-      - uses: dart-lang/setup-dart@v0.3
+      - uses: dart-lang/setup-dart@v1.0
         with:
           sdk: ${{ matrix.sdk }}
       - id: install
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6fda0a0..fa4b193 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,5 @@
+# 1.8.2-dev
+
 # 1.8.1
 
 * Fix a bug where the URL header for the highlights with multiple files would
diff --git a/pubspec.yaml b/pubspec.yaml
index 89599df..3343428 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,11 +1,11 @@
 name: source_span
-version: 1.8.1
+version: 1.8.2-dev
 
 description: A library for identifying source spans and locations.
 homepage: https://github.com/dart-lang/source_span
 
 environment:
-  sdk: ">=2.12.0-0.0 <3.0.0"
+  sdk: ">=2.12.0 <3.0.0"
 
 dependencies:
   collection: ^1.15.0
@@ -13,4 +13,4 @@
   term_glyph: ^1.2.0
 
 dev_dependencies:
-  test: ^1.16.0-nullsafety
+  test: ^1.16.0
diff --git a/test/file_test.dart b/test/file_test.dart
index 581f03f..dff51ee 100644
--- a/test/file_test.dart
+++ b/test/file_test.dart
@@ -2,8 +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:source_span/source_span.dart';
+import 'package:test/test.dart';
 
 void main() {
   late SourceFile file;
diff --git a/test/span_test.dart b/test/span_test.dart
index c27048e..348cc9e 100644
--- a/test/span_test.dart
+++ b/test/span_test.dart
@@ -2,11 +2,10 @@
 // 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:term_glyph/term_glyph.dart' as glyph;
-
 import 'package:source_span/source_span.dart';
 import 'package:source_span/src/colors.dart' as colors;
+import 'package:term_glyph/term_glyph.dart' as glyph;
+import 'package:test/test.dart';
 
 void main() {
   late bool oldAscii;
diff --git a/test/utils_test.dart b/test/utils_test.dart
index 02888df..293b300 100644
--- a/test/utils_test.dart
+++ b/test/utils_test.dart
@@ -2,8 +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:source_span/src/utils.dart';
+import 'package:test/test.dart';
 
 void main() {
   group('find line start', () {