chore: set max SDK version to <3.0.0 (#107)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8a3240c..f4e1c9f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.7.3+3
+
+* Set max SDK version to `<3.0.0`, and adjust other dependencies.
+
 ## 0.7.3+2
 
 * Fix constant evaluation analyzer error in `shelf_unmodifiable_map.dart`.
diff --git a/pubspec.yaml b/pubspec.yaml
index 74c78ab..1db9f8f 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,17 +1,21 @@
 name: shelf
-version: 0.7.3+2
-author: Dart Team <misc@dartlang.org>
+version: 0.7.3+3
+
 description: Web Server Middleware for Dart
+author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/dart-lang/shelf
+
 environment:
-  sdk: '>=2.0.0-dev.61.0 <2.0.0'
+  sdk: '>=2.0.0-dev.61.0 <3.0.0'
+
 dependencies:
-  async: '>=1.10.0 <3.0.0'
-  collection: '^1.5.0'
-  http_parser: '^3.1.0'
-  path: '^1.0.0'
-  stack_trace: '^1.0.0'
-  stream_channel: '^1.0.0'
+  async: ^2.0.7
+  collection: ^1.5.0
+  http_parser: ^3.1.0
+  path: ^1.0.0
+  stack_trace: ^1.0.0
+  stream_channel: ^1.0.0
+
 dev_dependencies:
-  http: '>=0.9.2 <0.12.0'
-  test: '^1.2.0'
+  http: ^0.11.3
+  test: ^1.2.0