simplify the register routes process

cmd/main.go

@@ -30,8 +30,7 @@ func main() {
 		TimeZone:   "America/New_York",
 	}))
 
-	authGroup := app.Group("/api/auth")
-	authGroup = auth.SetupRoutes(authGroup)
+	auth.SetupRoutes(app.Group("/api/auth"))
 
 	log.Fatal(app.Listen(":3000"))
 }