chore: do not upload to snap store (#570)

Copy paste of ipfs/ipfs-desktop#1069

Trying to fix

Author: amaury1093

packages/fether-electron/electron-builder.json

@@ -9,7 +9,7 @@
     "category": "public.app-category.productivity"
   },
   "productName": "Parity Fether",
-  "publish": "github",
+  "publish": ["github"],
   "win": {
     "icon": "icons/icon.ico",
     "publisherName": "Parity Technologies (UK) Ltd.",