prepare 5.4.0 release

Author: nyamsprod

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 All Notable changes to `PHP Domain Parser` **5.x** series will be documented in this file
 
-# Next - TBD
+# 5.4.0 - 2018-11-22
 
 ### Added
 

src/Cache.php

@@ -21,6 +21,7 @@
 use Psr\SimpleCache\CacheInterface;
 use Traversable;
 use function chmod;
+use function date_create_immutable;
 use function dirname;
 use function file_exists;
 use function file_get_contents;