Updated zend-session in require-dev to 2.8.5 to support PHP 7.2

Author: michalbundyra

composer.json

@@ -23,7 +23,7 @@
         "phpunit/phpunit": "^5.7.27 || ^6.5.8 || ^7.1.4",
         "zendframework/zend-coding-standard": "~1.0.0",
         "zendframework/zend-json": "^2.6.1",
-        "zendframework/zend-session": "^2.6.2"
+        "zendframework/zend-session": "^2.8.5"
     },
     "suggest": {
         "zendframework/zend-json": "Zend\\Json component",