Switch to using package:lints (#59)

Update the min SDK to 2.15.0 for `unawaited`.
diff --git a/.github/workflows/test-package.yml b/.github/workflows/test-package.yml
index fe6c6c1..ac76c8c 100644
--- a/.github/workflows/test-package.yml
+++ b/.github/workflows/test-package.yml
@@ -47,7 +47,7 @@
       matrix:
         # Add macos-latest and/or windows-latest if relevant for this package.
         os: [ubuntu-latest]
-        sdk: [2.12.0, dev]
+        sdk: [2.15.0, dev]
     steps:
       - uses: actions/checkout@v2
       - uses: dart-lang/setup-dart@v1
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 379eaf6..de9226e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,8 @@
 ## 4.1.1-dev
 
 - Apply `keepAlive` logic to `SocketException`s.
+- Switch from using `package:pedantic` to `package:lints`
+- Rev the minimum required SDK to 2.15.
 
 ## 4.1.0
 
diff --git a/analysis_options.yaml b/analysis_options.yaml
index 2a0ddfa..f767506 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -1,4 +1,5 @@
-include: package:pedantic/analysis_options.yaml
+include: package:lints/recommended.yaml
+
 analyzer:
   strong-mode:
     implicit-casts: false
@@ -7,6 +8,7 @@
     unused_element: error
     unused_import: error
     unused_local_variable: error
+
 linter:
   rules:
     - always_declare_return_types
diff --git a/lib/src/server/sse_handler.dart b/lib/src/server/sse_handler.dart
index 72cc919..13ce670 100644
--- a/lib/src/server/sse_handler.dart
+++ b/lib/src/server/sse_handler.dart
@@ -9,7 +9,6 @@
 import 'package:async/async.dart';
 import 'package:collection/collection.dart';
 import 'package:logging/logging.dart';
-import 'package:pedantic/pedantic.dart';
 import 'package:shelf/shelf.dart' as shelf;
 import 'package:stream_channel/stream_channel.dart';
 
diff --git a/pubspec.yaml b/pubspec.yaml
index 6f65957..4beae60 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -7,18 +7,18 @@
   requests.
 
 environment:
-  sdk: '>=2.12.0 <3.0.0'
+  sdk: '>=2.15.0 <3.0.0'
 
 dependencies:
   async: ^2.0.8
   collection: ^1.0.0
   logging: '>=0.11.3+2 <2.0.0'
   pool: ^1.5.0
-  pedantic: ^1.4.0
-  stream_channel: '>=1.6.8 <3.0.0'
   shelf: ^1.1.0
+  stream_channel: '>=1.6.8 <3.0.0'
 
 dev_dependencies:
+  lints: ^1.0.0
   shelf_static: '>=0.2.8 <2.0.0'
   test: ^1.5.3
   webdriver: ^3.0.0