Add swiftysynth (#14467)

Author: github-actions[bot]

packages.json

@@ -4707,6 +4707,7 @@
   "https://github.com/jiyimeta/swift-sheet-music.git",
   "https://github.com/jiyimeta/swift-spleeter.git",
   "https://github.com/jiyimeta/swift-wirelet.git",
+  "https://github.com/jiyimeta/swiftysynth.git",
   "https://github.com/jjc1138/tiny-events.git",
   "https://github.com/jjjkkkjjj/Matft.git",
   "https://github.com/jjochen/JJFloatingActionButton.git",