admin: Update SECURITY to reflect that 2.5 only gets critical fixes now (#4829)

Signed-off-by: Larry Gritz <lg@larrygritz.com>

Author: lgritz

SECURITY.md

@@ -9,7 +9,7 @@ security vulnerabilities.
 | ----------------- | ---------------------------------------------------- |
 | main              | :white_check_mark: :construction: ALL fixes immediately, but this is a branch under development with a frequently unstable ABI and occasionally unstable API. |
 | 3.0.x             | :white_check_mark: All fixes that can be backported without breaking ABI compatibility. New tagged releases monthly. |
-| 2.5.x             | :white_check_mark: All fixes that can be backported without breaking ABI compatibility. New tagged releases monthly. But be warned that probably by mid-2025, the 2.5.x family will move to a state of only receiving critical fixes, upon request, only if they can be easily backported. |
+| 2.5.x             | :warning: Bug fixes backported only if critical or upon request (and if we are able to cleanly backport). New tagged releases only occasionally. |
 | <= 2.4.x          | :x: No longer receiving patches of any kind.        |