[composer] Set dependencies for 1.7.9 release.

Author: Łukasz Serwatka

composer.json

@@ -12,7 +12,7 @@
     ],
     "require": {
         "php": "^7.1",
-        "ezsystems/ezpublish-kernel": "^7.5.8@dev",
+        "ezsystems/ezpublish-kernel": "^7.5.8",
         "netgen/query-translator": "^1.0.2"
     },
     "require-dev": {