bump version for release

Author: cmacdonald

README.md

@@ -1,4 +1,4 @@
-Terrier IR Platform - Terabyte Retriever v5.7
+Terrier IR Platform - Terabyte Retriever v5.9
 ---------------------------------------------
 ![Terrier Maven CI](https://github.com/terrier-org/terrier-core/workflows/Terrier%20Maven%20CI/badge.svg) [![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.terrier/terrier-platform/badge.svg)](https://maven-badges.herokuapp.com/maven-central/org.terrier/terrier-platform) 
 
@@ -36,4 +36,4 @@ citation licence.
 ------------------------
 > Webpage: <http://terrier.org>  
 > Contact: [School of Computing Science](http://www.dcs.gla.ac.uk/)  
-> Copyright (C) 2004-2022 [University of Glasgow](http://www.gla.ac.uk/). All Rights Reserved. 
+> Copyright (C) 2004-2024 [University of Glasgow](http://www.gla.ac.uk/). All Rights Reserved. 

doc/whats_new.md

@@ -1,12 +1,19 @@
 What's New in Terrier
 =====================
 
-Terrier 5.9 - XX/XX/XXX
+Terrier 5.9 - 2/5/2024
 -----------------------
 
+## Indexing
+ * Prevent negative free memory from ending indexing
+
 ## Retrieval
  * Fix problem with FatFull misassociating postings to documents [#246](https://github.com/terrier-org/terrier-core/pull/246). In PyTerrier, this makes the retrieval results/effectivenesss of `BatchRetrieve >> FeaturesBatchRetrieve` identical to `FeaturesBatchRetrieve(..., wmodel=...)`. 
 
+## Other
+* Bump logback by @dependabot
+* dont cutoff stacktraces during Unit tests
+
 Terrier 5.8 - 1/11/2023
 -----------------------