Fix for YT URL searches on Lavalink v4

Since the prior code for v3 uses list comprehension to build the tracks returned, we can check if we're using v4 and if the data[data_type] is a dictionary, and wrap it in a list to ensure the same behavior.

pomice/pool.py

@@ -837,6 +837,8 @@ class Node:
             )
 
         elif load_type in ("SEARCH_RESULT", "TRACK_LOADED", "track", "search"):
+            if self._version.major >= 4 and isinstance(data[data_type],dict):
+                data[data_type] = [data[data_type]]
             return [
                 Track(
                     track_id=track["encoded"],