Merge pull request #21 from dreamfactorysoftware/dependabot/composer/master/dreamfactory/df-core-approx-0.15.3

Update dreamfactory/df-core requirement from ~0.15.2 to ~0.15.3

Author: yaroslavmo

composer.json

@@ -30,7 +30,7 @@
   "minimum-stability": "dev",
   "prefer-stable": true,
   "require":     {
-    "dreamfactory/df-core":   "~0.15.2",
+    "dreamfactory/df-core":   "~0.15.3",
     "dreamfactory/df-system": "~0.2.1"
   },
   "autoload":    {