Update PHPUnit.

composer.json

@@ -67,7 +67,7 @@
         "phpdocumentor/phpdocumentor": "2.9.0",
         "phploc/phploc": "3.0.1",
         "phpmd/phpmd": "2.6.0",
-        "phpunit/phpunit": "5.7.9",
+        "phpunit/phpunit": "5.7.15",
         "sebastian/phpcpd": "2.0.4",
         "squizlabs/php_codesniffer": "2.8.1",
         "twig/twig": "1.27"

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "af0987e27f39230883fa8edeb531103b",
+    "content-hash": "7713f46c9d0c08afd51e8d33eea810b5",
     "packages": [
         {
             "name": "aferrandini/phpqrcode",
@@ -5831,16 +5831,16 @@
         },
         {
             "name": "phpunit/phpunit",
-            "version": "5.7.9",
+            "version": "5.7.15",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit.git",
-                "reference": "69f832b87c731d5cacad7f91948778fe98335fdd"
+                "reference": "b99112aecc01f62acf3d81a3f59646700a1849e5"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/69f832b87c731d5cacad7f91948778fe98335fdd",
-                "reference": "69f832b87c731d5cacad7f91948778fe98335fdd",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/b99112aecc01f62acf3d81a3f59646700a1849e5",
+                "reference": "b99112aecc01f62acf3d81a3f59646700a1849e5",
                 "shasum": ""
             },
             "require": {
@@ -5857,14 +5857,14 @@
                 "phpunit/php-text-template": "~1.2",
                 "phpunit/php-timer": "^1.0.6",
                 "phpunit/phpunit-mock-objects": "^3.2",
-                "sebastian/comparator": "~1.2.2",
+                "sebastian/comparator": "^1.2.4",
                 "sebastian/diff": "~1.2",
                 "sebastian/environment": "^1.3.4 || ^2.0",
                 "sebastian/exporter": "~2.0",
-                "sebastian/global-state": "^1.0 || ^2.0",
+                "sebastian/global-state": "^1.1",
                 "sebastian/object-enumerator": "~2.0",
                 "sebastian/resource-operations": "~1.0",
-                "sebastian/version": "~1.0|~2.0",
+                "sebastian/version": "~1.0.3|~2.0",
                 "symfony/yaml": "~2.1|~3.0"
             },
             "conflict": {
@@ -5909,7 +5909,7 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2017-01-28T06:14:33+00:00"
+            "time": "2017-03-02T15:22:43+00:00"
         },
         {
             "name": "phpunit/phpunit-mock-objects",