Updated dependencies and required PHP version

Fixes #55
Closes #56

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
+### Changed
+- updated dependencies (Mustache.php, Pimple)
+- minimum required PHP version 7.2.5 (was de-facto required by dependencies before)
+
 ## 3.3.5 - 2021-09-28
 
 ### Changed