Bump electron from 35.1.2 to 39.8.4 in /frontend

---
updated-dependencies:
- dependency-name: electron
  dependency-version: 39.8.4
  dependency-type: direct:development
...

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

Author: dependabot[bot]

frontend/npm-shrinkwrap.json

@@ -99,7 +99,7 @@
     "n-readlines": "^1.0.1"
   },
   "devDependencies": {
-    "electron": "^35.0.1",
+    "electron": "^39.8.4",
     "electron-builder": "^25.1.8",
     "@electron/packager": "^18.3.6"
   }