Path OS compatibility fix

Hello!

I found the way the path was handled didn't work in my Windows environment. The reason is that the paths in Windows use "\" instead of "/". I suggest this change to make the code cross-platform compatible. It uses the "parts" attribute of the path, so it is independent of the OS used.

Cheers!

gtzan.py

@@ -80,8 +80,8 @@ class Gtzan(datasets.GeneratorBasedBuilder):
         data = []
 
         for path in paths:
-            label = str(path).split("/")[-2]
-            name = str(path).split("/")[-1]
+            label = path.parts[-2]
+            name = path.parts[-1]
             if name in CORRUPTED_FILES:
                 continue