Use twig instead of templating engine to render about page

This restores compatibility with Contao 4.8 without changing default
configuration of the symfony framework bundle.

CHANGELOG.md

@@ -6,6 +6,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [3.1.5] - 2019-08-21
+
+### Fixed
+
+ - Use twig directly instead of templating component to restore Contao 4.8
+
 ## [3.1.4] - 2019-02-13
 
 ### Fixed