Update version to the next release v0.13

Author: meili-bot

README.md

@@ -48,7 +48,7 @@ You can install the **meilisearch** package by adding a few lines into `pubspec.
 
 ```yaml
 dependencies:
-  meilisearch: ^0.12.0
+  meilisearch: ^0.13.0
 ```
 
 Then open your terminal and update dart packages.

lib/src/version.dart

@@ -1,5 +1,5 @@
 class Version {
-  static const String current = '0.12.0';
+  static const String current = '0.13.0';
 
   static String get qualifiedVersion {
     return "Meilisearch Dart (v$current)";

pubspec.yaml

@@ -1,6 +1,6 @@
 name: meilisearch
 description: Meilisearch Dart is the Meilisearch API client for Dart and Flutter developers.
-version: 0.12.0
+version: 0.13.0
 homepage: https://meilisearch.com
 repository: https://github.com/meilisearch/meilisearch-dart
 issue_tracker: https://github.com/meilisearch/meilisearch-dart/issues