Update SECURITY.md

Author: peldax

SECURITY.md

@@ -4,8 +4,9 @@
 
 | Version | Supported          | PHP version | Status |
 | ------- | ------------------ |-------------|--------|
-| 1.x     | :heavy_check_mark: | 8.1         | Maintained and actively improved with new features.
+| > 1.3   | :heavy_check_mark: | 8.1         | Maintained and actively improved with new features.
 | 1.3.x   | :white_check_mark: | 8.0         | Maintained in bugfix only mode.
+| < 1.3   | :x:                | 8.0         | Please upgrade to 1.3 or later.
 | < 0.25  | :x:                | 7.4         | Please upgrade to 1.3 or later.
 
 ## Reporting a Vulnerability