Update composer.json

Author: Igor Chepurnoy

composer.json

@@ -16,7 +16,7 @@
     "require": {
         "php": ">=5.4.0",
         "yiisoft/yii2": "2.0.*",
-        "symfony/process": "2.6.*",
+        "symfony/process": "~3.2",
         "mtdowling/cron-expression": "~1.0",
         "league/climate": "^3.2"
     },