[flutter_plugin_android_lifecycle] Bump version for NNBD stable (flutter#3569)

Author: stuartmorgan-g

packages/flutter_plugin_android_lifecycle/CHANGELOG.md

@@ -1,15 +1,8 @@
-## 2.0.0-nullsafety.2
+## 2.0.0
 
+* Bump Dart SDK for null-safety compatibility.
 * Fix outdated links across a number of markdown files ([#3276](https://github.com/flutter/plugins/pull/3276))
 
-## 2.0.0-nullsafety.1
-
-* Fix example app SDK.
-
-## 2.0.0-nullsafety
-
-* Bump Dart SDK.
-
 ## 1.0.12
 
 * Update Flutter SDK constraint.

packages/flutter_plugin_android_lifecycle/pubspec.yaml

@@ -1,10 +1,10 @@
 name: flutter_plugin_android_lifecycle
 description: Flutter plugin for accessing an Android Lifecycle within other plugins.
-version: 2.0.0-nullsafety.2
+version: 2.0.0
 homepage: https://github.com/flutter/plugins/tree/master/packages/flutter_plugin_android_lifecycle
 
 environment:
-  sdk: ">=2.12.0-0 <3.0.0"
+  sdk: ">=2.12.0-259.9.beta <3.0.0"
   flutter: ">=1.12.13"
 
 dependencies: