Update supported versions in SECURITY.md to 2.x

Author: dash14

SECURITY.md

@@ -19,7 +19,8 @@ The following are **out of scope** (please report to the respective projects ins
 
 | Version | Supported |
 | ------- | --------- |
-| 1.x     | :white_check_mark: |
+| 1.x     | :x: |
+| 2.x     | :white_check_mark: |
 
 ## Reporting a Vulnerability