uninstall electron-spellcheck

Electron introduced native spell-checking in version 8, and this library
was subsequently abandoned.

Author: black-puppydog

package-lock.json

@@ -25,7 +25,6 @@
     "depject": "^4.1.1",
     "depnest": "^1.3.0",
     "electron-default-menu": "~1.0.1",
-    "electron-spellchecker": "^2.2.1",
     "electron-window-state": "^5.0.3",
     "escape-string-regexp": "^4.0.0",
     "fix-path": "^3.0.0",