Compile warning: var devcards.core/test-doc is not public

Hey, I am experimenting with dc/deftest and tried to implement some tests directly in devcards. Previously I wrote tests with lein doo, but this is not really satisfying.

However, I am getting the error message that test-doc is not public. I am not quite sure, why this error appears. I have many devcards in this project and they are all operating well. Also the other tests are all okay.

```clojure
(ns some.namespace
(:require
[cljs.test :refer [testing is are]]
[devcards.core :as dc]))

(dc/deftest foo
^--- var: devcards.core/test-doc is not public
"Sample card"
(testing "Fix me, I fail"
(is false)))
```

Some of my dependencies:
```edn
[org.clojure/clojure "1.10.0"]
[org.clojure/clojurescript "1.10.520"]
[devcards "0.2.6"]
[com.bhauman/figwheel-main "0.2.0"]
[com.bhauman/rebel-readline-cljs "0.1.4"]
```

Thanks for your help. I have no idea what could be wrong. I am using devcards in several projects and i love it, but this is a strange error message.