It looks like the :unused-namespaces linter is giving false positives when only constants are used from another namespace.

Example:

a.clj

(ns proj.a)

(def ^:const version "1.0.0")

b.clj

(ns proj.b
  (:require [proj.a :as a]))

(defn project-info []
   {:version a/version})

Error

src/proj/b.clj:1:1: unused-namespaces: Namespace proj.a is never used in proj.b