Bump electron-builder from 19.55.2 to 20.3.1

Bumps [electron-builder](https://github.com/electron-userland/electron-builder) from 19.55.2 to 20.3.1.
- [Release notes](https://github.com/electron-userland/electron-builder/releases)
- [Changelog](https://github.com/electron-userland/electron-builder/blob/master/CHANGELOG.md)
- [Commits](electron-userland/electron-builder@v19.55.2...v20.3.1)

Signed-off-by: dependabot[bot] <support@dependabot.com>

package.json

@@ -133,7 +133,7 @@
     "del": "^3.0.0",
     "devtron": "^1.1.0",
     "electron": "^1.8.2",
-    "electron-builder": "^19.27.2",
+    "electron-builder": "^20.3.1",
     "electron-debug": "~1.4.0",
     "electron-devtools-installer": "^2.0.1",
     "eslint": "^4.18.2",