CONTRIBUTING: Add clause against "AI"

In quotes, because AI generally means a lot more than what people use
the word for nowadays.

Copied straight from GoToSocial's stub code of conduct.

Signed-off-by: Maxime “pep” Buquet <[email protected]>

Author: Ppjet6

CONTRIBUTING.md

@@ -19,6 +19,11 @@ The earlier we catch bugs and fix them, the less chances they have to confuse
 users of our library, or make end-users give up on software developed using
 this library. This also helps improving other software in the ecosystem.
 
+We will not accept changes (code or otherwise) created with the aid of "AI"
+tooling. "AI" models are trained at the expense of underpaid workers filtering
+inputs of abhorrent content, and does not respect the owners of input content.
+Ethically, it sucks.
+
 ## Keep commits short and meaningful
 
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