update CHANGELOG.md and pubspec.yaml versions

Author: juliocbcotta

packages/firebase_database/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 3.0.7
+
+* Fix possible NullPointerException when plugin is registered without a valid Activity.
+
 ## 3.0.6
 
 * Update documentation to reflect new repository location.

packages/firebase_database/pubspec.yaml

@@ -3,7 +3,7 @@ description: Flutter plugin for Firebase Database, a cloud-hosted NoSQL database
   with realtime data syncing across Android and iOS clients, and offline access.
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/FirebaseExtended/flutterfire/tree/master/packages/firebase_database
-version: 3.0.6
+version: 3.0.7
 
 flutter:
   plugin: