Add model for render texture agent (#2863)

UnitySDK/Assets/ML-Agents/Examples/GridWorld/Scenes/GridWorld.unity

   m_ReflectionIntensity: 1
   m_CustomReflection: {fileID: 0}
   m_Sun: {fileID: 0}
-  m_IndirectSpecularColor: {r: 0.44971162, g: 0.49977726, b: 0.5756362, a: 1}
+  m_IndirectSpecularColor: {r: 0.4497121, g: 0.49977785, b: 0.57563704, a: 1}
 --- !u!157 &3
 LightmapSettings:
   m_ObjectHideFlags: 0
     vectorActionSize: 05000000
     vectorActionDescriptions: []
     vectorActionSpaceType: 0
-  m_Model: {fileID: 11400000, guid: 07afbd1d35ed345eeb850fcbb59eae0b, type: 3}
+  m_Model: {fileID: 11400000, guid: a812f1ce7763a4a0c912717f3594fe20, type: 3}
   m_InferenceDevice: 0
   m_UseHeuristic: 0
   m_BehaviorName: GridWorld