Revert default RSS feed URL after customizing routes

I am using Ghost (Pro) and I did some simple customization to my routes.yaml as follows:

routes:
  /:
    template: home
    data: page.home

collections:
  /posts/:
    permalink: /{slug}/
    template: index

taxonomies:
  tag: /tag/{slug}/
  author: /author/{slug}/

After doing this, I realized that the default RSS feed for all posts moved from /rss/ to /posts/rss. How do I revert that URL to /rss/ while keeping my /posts/ routing? I did read this but I don’t want to use a custom template. The default one is good enough for me. How do I do this?

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