Bump PHP required versions.

Author: JJJ

composer.json

@@ -4,7 +4,7 @@
   "homepage": "https://github.com/stuttter/wp-chosen",
   "type": "wordpress-plugin",
   "require": {
-    "php": ">=5.2",
+    "php": ">=7.0",
     "composer/installers": "^1.0"
   },
   "license": "GPL-2.0-or-later",

wp-chosen.php

@@ -7,7 +7,7 @@
  * Author URI:        https://jjj.blog
  * Description:       Makes unwieldy select boxes more user-friendly
  * License:           GPLv2 or later
- * Requires at least: 5.6
+ * Requires at least: 5.7
  * Requires PHP:      7.0
  * Version:           6.1.0
  */