Support go run on action (#12)

Reviewed-on: https://gitea.com/gitea/act/pulls/12
Reviewed-by: Jason Song <i@wolfogre.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-committed-by: Lunny Xiao <xiaolunwen@gmail.com>

pkg/model/action.go

@@ -42,6 +42,8 @@ const (
 	ActionRunsUsingDocker = "docker"
 	// ActionRunsUsingComposite for running composite
 	ActionRunsUsingComposite = "composite"
+	// ActionRunsUsingGo for running with go
+	ActionRunsUsingGo = "go"
 )
 
 // ActionRuns are a field in Action