Changed sin to tan in angle calculation

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Lighting/HDLightEditor.cs

                             var angleA = settings.spotAngle.floatValue * Mathf.Deg2Rad;
 
                             var halfAngle = angleA * 0.5f; // half of the smallest angle
-                            var length = Mathf.Sin(halfAngle); // half length of the smallest side of the rectangle
+                            var length = Mathf.Tan(halfAngle); // half length of the smallest side of the rectangle
                             length *= aspectRatio; // half length of the bigest side of the rectangle
                             halfAngle = Mathf.Atan(length); // half of the bigest angle