Allow DoctrineBundle 2.0

Already done in https://github.com/symfony/orm-pack/blob/master/composer.json

Author: fabpot

composer.json

@@ -8,7 +8,7 @@
     "api-platform/core": "^2.1",
     "doctrine/annotations": "^1.0",
     "doctrine/orm": "^2.4.5",
-    "doctrine/doctrine-bundle": "^1.6",
+    "doctrine/doctrine-bundle": "^1.6 || ^2.0",
     "nelmio/cors-bundle": "^1.5",
     "phpdocumentor/reflection-docblock": "^3.0 || ^4.0",
     "symfony/asset": "*",