Update action.yml (#30)

Author: mit-mit

action.yml

@@ -1,5 +1,8 @@
 name: "Setup Dart SDK"
 description: "Setup the Dart SDK, and add it to the PATH"
+branding:
+  icon: check-circle
+  color: blue
 inputs:
   sdk:
     description: "The channel, or a specific version from a channel to install ('stable', 'beta', 'dev', '2.7.2', '2.12.0-1.4.beta'). Using one of the three channels instead of a version will give you the latest version published to that channel."