inputstream.rtmp v2.0.8 for Kodi v18 (Leia) has been released.
You can...
Wait upto 24 hours for your repository and add-on to update automatically, assuming you have not disabled these settings. (Option 3 if you do not want to wait)
Go to Settings > Add-ons and force a repository update from the left sideblade menu by selecting Check for updates. You may need to wait until the update reaches the servers in your part of the world. (Option 3 if it is still not available)