Prepare notus release

packages/notus/CHANGELOG.md

+## 0.1.5
+
+* Bumped minimum Dart SDK version to 2.2
+* Upgraded dependencies and resolved analyzer errors
+
 ## 0.1.4
 
 * Fixed insertion of embeds when selection is not empty (#115)

packages/notus/pubspec.yaml

 name: notus
 description: Platform-agnostic rich text document model based on Delta format and used in Zefyr editor.
-version: 0.1.4
+version: 0.1.5
 author: Anatoly Pulyaevskiy <anatoly.pulyaevskiy@gmail.com>
 homepage: https://github.com/memspace/zefyr