replace request "dependency"

[vwegert]

The module has an unused dependency to request in node_helper.js (see also MagicMirrorOrg/MagicMirror#2468) that will prevent MM from loading after a recent upgrade.

`[17.10.2021 10:12.05.508] [LOG] Starting MagicMirror: v2.17.1
[17.10.2021 10:12.05.512] [LOG] Loading config ...
[17.10.2021 10:12.05.516] [ERROR] WARNING! Could not load config file. Starting with default configuration. Error found: Error: Cannot find module 'request'
Require stack:

• /home/magicmirror/MagicMirror/modules/MMM-RandomBackground/node_helper.js
• /home/magicmirror/MagicMirror/js/app.js
• /home/magicmirror/MagicMirror/serveronly/index.js
  `

(My PR for doc improvements has not been merged for a year - is this module still maintained at all?)

[Ultimatum22]

I don't have a MagicMirror running anymore so this is not maintained. Sorry I missed the PR, I merged it. If you can submit a PR I will merge this so the plugin works again.