Bump php-sdk to version v2.5.9

Author: romainneutron

CHANGELOG

@@ -1,6 +1,10 @@
 CHANGELOG
 =========
 
+* v2.5.9 (2025-10-15)
+
+  - Prevent committing debug code
+
 * v2.5.8 (2025-08-13)
 
   - Fix Client's retry logic

src/Blackfire/Client.php

@@ -28,7 +28,7 @@ class Client
 {
     const MAX_RETRY = 60;
     const NO_REFERENCE_ID = '00000000-0000-0000-0000-000000000000';
-    const VERSION = '2.5.8';
+    const VERSION = '2.5.9';
 
     private $config;
     private $collabTokens;