electron_app: Remove Seshat from the dependencies.

electron_app/package.json

@@ -5,16 +5,11 @@
   "version": "1.4.2",
   "description": "A feature-rich client for Matrix.org",
   "author": "New Vector Ltd.",
-  "scripts": {
-    "build": "electron-build-env --electron 6.0.3 neon build seshat-node --release",
-    "postinstall": "yarn build"
-  },
   "dependencies": {
     "auto-launch": "^5.0.1",
     "electron-store": "^2.0.0",
     "electron-window-state": "^4.1.0",
     "minimist": "^1.2.0",
-    "png-to-ico": "^1.0.2",
-    "matrix-seshat": "^0.3.0"
+    "png-to-ico": "^1.0.2"
   }
 }