[CORE][COMPOSER] Ensure we are compatible with PHP 7.0.0

composer.json

@@ -30,7 +30,7 @@
     },
     "require-dev": {
         "phpdocumentor/phpdocumentor": "^2.9",
-        "phpunit/phpunit": "^8.2",
+        "phpunit/phpunit": "^6.5",
         "psy/psysh": "^0.9.9"
     },
     "suggest": {
@@ -67,7 +67,10 @@
     "config": {
         "optimize-autoloader": true,
         "preferred-install": "dist",
-        "sort-packages": true
+        "sort-packages": true,
+        "platform": {
+            "php": "7.0.0"
+        }
     },
     "scripts": {
         "post-update-cmd": [

tests/Core/XmppValidateTest.php

@@ -31,7 +31,6 @@ use PHPUnit\Framework\TestCase;
 use XmppPlugin;
 
 require_once INSTALLDIR . '/lib/common.php';
-
 require_once INSTALLDIR . '/plugins/Xmpp/XmppPlugin.php';
 
 final class XmppValidateTest extends TestCase