Update flutter@stable for task add

I expect the build would fail with the following change from https://github.com/bradyt/taskw-dart/commit/6aebd3e74d3079a52d553a60b542882f4ef1c6ed.

@@ -673,5 +673,5 @@ packages:
     source: hosted
     version: "3.1.0"
 sdks:
-  dart: ">=2.13.0 <3.0.0"
+  dart: ">=2.14.0 <3.0.0"
   flutter: ">=2.0.0"

As well as for a later commit https://github.com/bradyt/taskw-dart/commit/c5b53059e3b2b769935bb6c7bf60155ddfa98520.

modified   task/pubspec.lock
@@ -674,4 +674,4 @@ packages:
     version: "3.1.0"
 sdks:
   dart: ">=2.14.0 <3.0.0"
-  flutter: ">=2.0.0"
+  flutter: ">=2.5.0"
modified   task/pubspec.yaml
@@ -7,6 +7,7 @@ version: 0.1.1+0.0.0
 
 environment:
   sdk: ">=2.12.0 <3.0.0"
+  flutter: ">=2.5.0 <3.0.0"
 
 dependencies:
   crypto: