Symantec Clicktime Protection is no longer scanning the link you have opened. The site you are trying to visit may be harmful. If you know the site is safe, you can go to it directly by clicking on the original URL below:
https://github.com/notifications/unsubscribe-auth/A36TO2TOWBSH2NU3QQY3IS3WGJ2N5ANCNFSM6AAAAAARU2GKY4
Learn more about Advanced Threat Protection and how Symantec can help you.