[composer] Set dependencies for 2.0.0-beta1 release

Author: Łukasz Serwatka

composer.json

@@ -19,8 +19,8 @@
     "prefer-stable": true,
     "require": {
         "php": "^7.3",
-        "ezsystems/ezpublish-kernel": "^8.0@dev",
-        "ezsystems/ezplatform-admin-ui": "^2.0@dev",
+        "ezsystems/ezpublish-kernel": "^8.0@beta",
+        "ezsystems/ezplatform-admin-ui": "^2.0@beta",
         "jms/translation-bundle": "^1.4",
         "symfony/dependency-injection": "^4.3",
         "symfony/http-kernel": "^4.3",