Remove no_graphics

Author: maryamziaa

colab/Colab_UnityEnvironment_1_Run.ipynb

@@ -180,7 +180,7 @@
     "\n",
     "from mlagents_envs.registry import default_registry\n",
     "\n",
-    "env = default_registry[env_id].make(no_graphics=True)"
+    "env = default_registry[env_id].make()"
    ],
    "execution_count": 3,
    "outputs": [