remove prepublish script

We don't publish the desktop app to npm anymore

package.json

@@ -103,7 +103,6 @@
     "install-system-deps": "brew install fakeroot dpkg",
     "open-config": "node ./bin/open-config.js",
     "package": "node ./bin/package.js",
-    "prepublish": "npm run build",
     "start": "npm run build && electron .",
     "test": "standard && depcheck --ignores=standard,babel-eslint --ignore-dirs=build,dist && node ./bin/extra-lint.js",
     "test-integration": "npm run build && node ./test",