Error installing shynitest from github

I am trying to install shinytest using devtools::install_github("rstudio/shinytest")and I get the error below. What could I do?

Skipping install of 'shinytest' from a github remote, the SHA1 (443cd389) has not changed since last install.
  Use `force = TRUE` to force installation

As the message is telling you, you already have shinytest installed and you have the last version. So there is nothing to install.
You don't have an error. Everything works fine.