[unity] Fixed shader compile error occurring during build on Unity URP versions 12.x and 13.x. See related commit 2f1b0b8. (Not related to last commit 1fa6c2e.)

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/Include/Spine-Common-URP.hlsl

@@ -14,7 +14,11 @@
 #ifdef _LIGHT_LAYERS
 uint GetMeshRenderingLayerBackwardsCompatible()
 {
+    #if IS_URP_14_OR_NEWER
     return GetMeshRenderingLayer();
+    #else
+    return GetMeshRenderingLightLayer();
+    #endif
 }
 #else
 uint GetMeshRenderingLayerBackwardsCompatible()