Remove unnecessary `maybe_map/1`

Thought slightly harder and realized this was unnecessary.
diff --git a/src/jiffy.erl b/src/jiffy.erl
index 1f3e2ad..6af15b5 100644
--- a/src/jiffy.erl
+++ b/src/jiffy.erl
@@ -137,7 +137,7 @@
 finish_decode(Vals) when is_list(Vals) ->
     finish_decode_arr(Vals, []);
 finish_decode({has_trailer, Value, Rest}) ->
-    {has_trailer, maybe_map(finish_decode(Value)), Rest};
+    {has_trailer, finish_decode(Value), Rest};
 finish_decode(Val) ->
     maybe_map(Val).