chore: Update SECURITY.md (#2512)

Author: Jason3S

SECURITY.md

@@ -4,8 +4,8 @@
 
 | Version | Supported          |
 | ------- | ------------------ |
+| 8.x     | :white_check_mark: |
 | 7.x     | :white_check_mark: |
-| 6.x     | :white_check_mark: |
 
 ## Reporting a Vulnerability