build: Set minimal flutter version

deandreamatias · deandreamatias · commit 384763d40924 · 2022-07-10T18:54:07.000+02:00
diff --git a/pubspec.yaml b/pubspec.yaml
@@ -5,6 +5,7 @@ homepage: https://github.com/danvick/form_builder_file_picker
 
 environment:
   sdk: '>=2.12.0 <3.0.0'
+  flutter: '>=3.0.0'
 
 dependencies:
   community_material_icon: ^5.9.55
