Update minimum dart sdk (powersync-ja#48)

Author: mugikhan

pubspec.yaml

@@ -3,7 +3,13 @@ description: High-performance asynchronous interface for SQLite on Dart and Flut
 version: 0.7.0
 repository: https://github.com/powersync-ja/sqlite_async.dart
 environment:
-  sdk: ">=3.2.0 <4.0.0"
+  sdk: ">=3.4.0 <4.0.0"
+
+topics:
+  - sqlite
+  - async
+  - sql
+  - flutter
 
 dependencies:
   sqlite3: "^2.4.4"