Remove call to `persistent!` in cljs lru print function
Remove call to `persistent!` in cljs lru print function

no longer pased on transients. And even if it were calling persistent
on a transient in a side-effecting operation that changes the
transient.

This error would manifest itself just by calling the lru function:

```cljs
(require '[datascript.lru :as lru])
(lru/lru 3)

```

tonsky/datascript,tonsky/datascript,tonsky/datascript