Merge pull request #4921 from Unity-Technologies/fix-permission-timers

Use more generic exception catching

com.unity.ml-agents/CHANGELOG.md

 - Removed unnecessary memory allocations in `SideChannelManager.GetSideChannelMessage()` (#4886)
 - Removed several memory allocations that happened during inference. On a test scene, this
   reduced the amount of memory allocated by approximately 25%. (#4887)
+- Properly catch permission errors when writing timer files. (#4921)
 
 #### ml-agents / ml-agents-envs / gym-unity (Python)
 - Fixed a bug that would cause an exception when `RunOptions` was deserialized via `pickle`. (#4842)

com.unity.ml-agents/Runtime/Timer.cs

                 SaveJsonTimers(fs);
                 fs.Close();
             }
-            catch (IOException)
+            catch (SystemException)
-                // It's possible we don't have write access to the directory.
+                // We may not have write access to the directory.
                 Debug.LogWarning($"Unable to save timers to file {filename}");
             }
 #endif