Remove support for PHP 5.2

Author: thePanz

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Updated changelog to comply to [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) specification
 ### Deprecated
 ### Removed
+- Remove support for PHP 5.2
 ### Fixed
 - Cannot declare self-referencing constant 'Doctrine_Query::STATE_CLEAN' [PR-71](https://github.com/FriendsOfSymfony1/doctrine1/pull/71)
 - Fix PHP 7.3 backward incompatible with continue statements [PR-67](https://github.com/FriendsOfSymfony1/doctrine1/pull/67)

composer.json

@@ -20,7 +20,7 @@
         }
     ],
     "require": {
-        "php": ">=5.2.3",
+        "php": ">=5.3",
         "ext-mbstring": "*",
         "ext-pdo": "*"
     },