use Debug.AssertFormat to avoid string formatting in DEBUG (#4879)

com.unity.ml-agents/Runtime/Sensors/SensorShapeValidator.cs

             {
                 // Check for compatibility with the other Agents' Sensors
                 // TODO make sure this only checks once per agent
-                Debug.Assert(m_SensorShapes.Count == sensors.Count, $"Number of Sensors must match. {m_SensorShapes.Count} != {sensors.Count}");
+                Debug.AssertFormat(
+                    m_SensorShapes.Count == sensors.Count,
+                    "Number of Sensors must match. {0} != {1}",
+                    m_SensorShapes.Count,
+                    sensors.Count
+                );
                 for (var i = 0; i < Mathf.Min(m_SensorShapes.Count, sensors.Count); i++)
                 {
                     var cachedShape = m_SensorShapes[i];