update sdk

example/pubspec.yaml

@@ -3,7 +3,7 @@ description: Demonstrates how to use the fluwx plugin.
 publish_to: 'none'
 
 environment:
-  sdk: ">=2.6.0 <3.0.0"
+  sdk: ">=2.12.0-0 <3.0.0"
 
 dependencies:
   flutter:

pubspec.yaml

@@ -4,7 +4,7 @@ version: 3.1.0-nullsafety.2
 homepage: https://github.com/JarvanMo/fluwx
 
 environment:
-  sdk: ">=2.6.0 <3.0.0"
+  sdk: ">=2.12.0-0 <3.0.0"
   flutter: ">=1.12.0 <2.0.0"
 
 dependencies: