fix php 8.1 deprecations (#3648)

* show session maxlifetime in doctor
* rephrase compatibility in release notes
* bump version

src/Constants.php

@@ -17,11 +17,11 @@ class Constants
     /**
      * The current release version
      */
-    public const VERSION = '1.29.0';
+    public const VERSION = '1.29.1';
     /**
      * The current release: major * 10000 + minor * 100 + patch
      */
-    public const VERSION_ID = 12900;
+    public const VERSION_ID = 12901;
     /**
      * The current release status, either "stable" or "dev"
      */