Migrated project to v2

When running "flutter pub get", flutter complained that the
project needed to be upgraded to v2. This patch follows the
suggested upgrade steps outlined on the wiki.

https://github.com/flutter/flutter/wiki/Upgrading-pre-1.12-Android-projects

The plugin `audioplayers` requires your app to be migrated to the Android embedding v2.

android/app/src/main/AndroidManifest.xml

@@ -6,11 +6,11 @@
          additional functionality it is fine to subclass or reimplement
          FlutterApplication and put your custom class here. -->
     <application
-        android:name="io.flutter.app.FlutterApplication"
+        android:name="${applicationName}"
         android:label="flutters"
         android:icon="@mipmap/ic_launcher">
         <activity
-            android:name=".MainActivity"
+            android:name="io.flutter.embedding.android.FlutterActivity"
             android:launchMode="singleTop"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"

lib/generated_plugin_registrant.dart

@@ -2,6 +2,7 @@
 // Generated file. Do not edit.
 //
 
+// ignore_for_file: directives_ordering
 // ignore_for_file: lines_longer_than_80_chars
 
 import 'package:audioplayers/audioplayers_web.dart';

pubspec.lock

@@ -7,7 +7,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0"
+    version: "2.8.2"
   audioplayers:
     dependency: transitive
     description:
@@ -35,14 +35,14 @@ packages:
       name: characters
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0"
+    version: "1.3.1"
   clock:
     dependency: transitive
     description:
@@ -141,14 +141,21 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.10"
+    version: "0.12.11"
+  material_color_utilities:
+    dependency: transitive
+    description:
+      name: material_color_utilities
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.1.3"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0"
+    version: "1.7.0"
   ordered_set:
     dependency: transitive
     description:
@@ -244,7 +251,7 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0"
+    version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
@@ -286,7 +293,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.19"
+    version: "0.4.8"
   typed_data:
     dependency: transitive
     description:
@@ -342,7 +349,7 @@ packages:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0"
+    version: "2.1.1"
   win32:
     dependency: transitive
     description:
@@ -358,5 +365,5 @@ packages:
     source: hosted
     version: "0.2.0"
 sdks:
-  dart: ">=2.12.0 <3.0.0"
+  dart: ">=2.14.0 <3.0.0"
   flutter: ">=1.20.0"