[unity] Fixed previous bugfix, Unity defines UNITY_2020_3_OR_NEWER and UNITY_2020_3_16 but not UNITY_2020_3_16_OR_NEWER. See #2101.

spine-unity/Assets/Spine/Editor/spine-unity/Editor/Utility/SpineBuildProcessor.cs

@@ -36,6 +36,13 @@
 #define HAS_ON_POSTPROCESS_PREFAB
 #endif
 
+#if !(UNITY_2020_3_1 || UNITY_2020_3_2 || UNITY_2020_3_3 || UNITY_2020_3_4 || UNITY_2020_3_5 || UNITY_2020_3_6 || UNITY_2020_3_7 || UNITY_2020_3_8 || UNITY_2020_3_9 || UNITY_2020_3_10 || UNITY_2020_3_11 || UNITY_2020_3_12 || UNITY_2020_3_13 || UNITY_2020_3_14 || UNITY_2020_3_15)
+#define UNITY_2020_3_16_OR_NEWER
+#endif
+#if !(UNITY_2021_1_1 || UNITY_2021_1_2 || UNITY_2021_1_3 || UNITY_2021_1_4 || UNITY_2021_1_5 || UNITY_2021_1_6 || UNITY_2021_1_7 || UNITY_2021_1_8 || UNITY_2021_1_9 || UNITY_2021_1_10 || UNITY_2021_1_11 || UNITY_2021_1_12 || UNITY_2021_1_13 || UNITY_2021_1_14 || UNITY_2021_1_15 || UNITY_2021_1_16)
+#define UNITY_2021_1_17_OR_NEWER
+#endif
+
 #if (UNITY_2020_3 && UNITY_2020_3_16_OR_NEWER) || UNITY_2021_1_17_OR_NEWER
 #define HAS_SAVE_ASSET_IF_DIRTY
 #endif