fix: absolute redirects in production

In production when accessing a URL without a trailing `/`, the nginx
server redirects absolutely and thus navigating to the herokuapp instead
of leaving the user in `www.electronjs.org`.

app.json

@@ -4,7 +4,7 @@
       "url": "heroku/nodejs"
     },
     {
-      "url": "https://github.com/hone/heroku-buildpack-static"
+      "url": "https://github.com/molant/heroku-buildpack-static"
     }
   ]
 }

static.json

@@ -1,6 +1,7 @@
 {
     "root": "build/",
     "clean_urls": true,
+    "absolute_redirect": false,
     "headers":{
         "/**":{
             "Cache-Control": "no-cache"