Fixed unity version in readme

Updated unity version to the right one

Author: smitdylan2001

README.md

@@ -4,7 +4,7 @@ Generic sparse octree and quadtree
 that store objects together with their axis aligned bounding boxes (AABB's)
 
 Written in C# for Unity's burst compiler and the ECS/DOTS framework.
-Tested with Unity 2021.1.3.11f1
+Tested with Unity 2021.3.11f1
 
 ### Supported queries:
 - Raycast
@@ -220,4 +220,4 @@ Nearest neighbour search:
 https://stackoverflow.com/a/41306992
 
 AnyPath, my pathfinding library on the Unity Asset store:
-https://assetstore.unity.com/packages/tools/ai/anypath-213200
+https://assetstore.unity.com/packages/tools/ai/anypath-213200