Drop php 5.6 support

Author: vinkla

composer.json

@@ -16,7 +16,7 @@
         }
     ],
     "require": {
-        "php": "^5.6.4 || ^7.0",
+        "php": "^7.0",
         "wpackagist-plugin/polylang": "^1.9"
     },
     "autoload": {
@@ -35,7 +35,7 @@
     },
     "extra":{
         "branch-alias": {
-            "dev-master": "1.1-dev"
+            "dev-master": "1.2-dev"
         }
     },
     "minimum-stability": "dev",

src/helpers.php

@@ -9,6 +9,8 @@
  * file that was distributed with this source code.
  */
 
+declare(strict_types=1);
+
 if (!function_exists('register_translations')) {
     /**
      * Register translations.
@@ -45,7 +47,7 @@ function register_translations(array $groups, $multiline = false)
      *
      * @return string
      */
-    function trans($key, $lang = null)
+    function trans(string $key, string $lang = null): string
     {
         if (!function_exists('pll__')) {
             throw new BadFunctionCallException('Please active the Polylang plugin.');