It's not possible to completely hide the robots.txt file from appearing in search engine results, as it is a publicly accessible file intended to provide information to web robots (such as search engine crawlers) about which parts of a website they should and shouldn't access.
However, you can limit the visibility of the file by using the "noindex" directive in the robots.txt file, like this:
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User-agent: * Disallow: / Noindex: /robots.txt
This tells search engines not to index the contents of the robots.txt file, which should reduce its visibility in search results. However, this is not a foolproof method, as the file may still appear in search results, particularly if it is linked from other pages on the web.