add asset propagation for giftbox texture

docs/release-notes.md

@@ -6,6 +6,7 @@
   * Fixed crash loading mods with corrupted translation files.
 
 * For mod authors:
+  * Added asset propagation for `LooseSprites\Giftbox`.
   * Improved SMAPI's crossplatform read/writing of `Color`, `Point`, `Rectangle`, and `Vector2` in JSON to support nullable fields too.
 
 * For the web UI:

src/SMAPI/Metadata/CoreAssetPropagator.cs

@@ -414,6 +414,10 @@ namespace StardewModdingAPI.Metadata
                     SpriteText.coloredTexture = content.Load<Texture2D>(key);
                     return true;
 
+                case "loosesprites\\giftbox": // Game1.LoadContent
+                    Game1.giftboxTexture = content.Load<Texture2D>(key);
+                    return true;
+
                 case "loosesprites\\nightbg": // Game1.LoadContent
                     Game1.nightbg = content.Load<Texture2D>(key);
                     return true;