Improve redis configuration

* version bump to 3.9.7
* update changelog

CHANGELOG.md

@@ -8,6 +8,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### v3.9.x - [Unreleased]
 
+### v3.9.7 - 2019-08-02
+
 #### Added
 
 - MySQL configuration tuning
@@ -28,6 +30,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Removed WordOps version from the Nginx header X-Powered-By to avoid possible security issues
 - Several code quality improvements to speed up WordOps execution
 - Few adjustements on PHP-FPM configuration (max_input_time,opcache.consistency_checks)
+-
 
 #### Fixed
 
@@ -35,6 +38,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fail2ban standalone install
 - `wo stack purge --all` error due to PHP7.3 check
 - Nginx helper configuration during plugin install for Nginx fastcgi_cache and redis-cache
+- phpRedisAdmin stack installation
+- Fixed Travis CI build on pull requests
 
 ### v3.9.6.2 - 2019-07-24