Update Vespa version to 8.659.18. (#4587)

Co-authored-by: kkraune <bot+actions@vespa.ai>

Author: github-actions[bot]

_config.yml

@@ -107,4 +107,4 @@ defaults:
       index : true
 
 variables:
-  vespa_version: "8.658.52"
+  vespa_version: "8.659.18"