ClojureScript: Fix test with regexp format

In ClojureScript str adds slashes (/) around original regexp (because it relies on JavaScript's toString method implementation).
Since this is by no means a bug here, I wrapped the compared regexp in a str as well to make the test pass with ClojureScript.
Remove crossovers from cljsbuild configuration to prevent some warnings

Crossovers are deprecated and they were already removed from project dependencies.
Keeping this key causes warnings about using deprecated features and missing dependencies.