Upgrade to eb 20.8.2 and eu 2.21.4

Author: iffy

package.json

@@ -9,11 +9,11 @@
   },
   "devDependencies": {
     "electron": "^1.7.9",
-    "electron-builder": "^19.43.3"
+    "electron-builder": "^20.8.2"
   },
   "dependencies": {
     "electron-log": "^1.3.0",
-    "electron-updater": "^2.15.0"
+    "electron-updater": "^2.21.4"
   },
   "build": {
     "appId": "com.github.iffy.electronupdaterexample",