Update README.md

Author: demiankatz

README.md

@@ -9,6 +9,9 @@ Framework 2.x.
 
 Changelog
 ---------
+** v1.3.1 **
+* Bug fixes (including improved PHP 8 compatibility).
+
 ** v1.3.0 **
 * Added Laminas integration.
 
@@ -19,4 +22,4 @@ Changelog
 * Added openAccessFilter option to support s.oaf parameter.
 
 ** v1.0.0 **
-* Initial stable release.
+* Initial stable release.