Use matterbridge vendored slack

vendor/github.com/nlopes/slack/examples/files/files.go

@@ -1,30 +0,0 @@
-package main
-
-import (
-	"fmt"
-
-	"github.com/nlopes/slack"
-)
-
-func main() {
-	api := slack.New("YOUR_TOKEN_HERE")
-	params := slack.FileUploadParameters{
-		Title: "Batman Example",
-		//Filetype: "txt",
-		File: "example.txt",
-		//Content:  "Nan Nan Nan Nan Nan Nan Nan Nan Batman",
-	}
-	file, err := api.UploadFile(params)
-	if err != nil {
-		fmt.Printf("%s\n", err)
-		return
-	}
-	fmt.Printf("Name: %s, URL: %s\n", file.Name, file.URL)
-
-	err = api.DeleteFile(file.ID)
-	if err != nil {
-		fmt.Printf("%s\n", err)
-		return
-	}
-	fmt.Printf("File %s deleted successfully.\n", file.Name)
-}