chore: Simplify security policy

Author: halostatue

SECURITY.md

@@ -30,16 +30,7 @@ All issues raised must be demonstrated on the minimum supported Ruby version.
 Report vulnerabilities via the [Tidelift security contact][tidelift]. Tidelift
 will coordinate the fix and disclosure.
 
-Alternatively, create a [private vulnerability report][advisory] with GitHub or
-send an email to [security@ruby.halostatue.ca][email] with the text `diff-lcs`
-in the subject. Emails sent to this address should be encrypted using [age][age]
-with the following public key:
-
-```
-age1fc6ngxmn02m62fej5cl30lrvwmxn4k3q2atqu53aatekmnqfwumqj4g93w
-```
+Alternatively, create a [private vulnerability report][advisory] with GitHub.
 
 [advisory]: https://github.com/halostatue/diff-lcs/security/advisories/new
-[age]: https://github.com/FiloSottile/age
-[email]: mailto:security@ruby.halostatue.ca
 [tidelift]: https://tidelift.com/security