Update NSynth.py

Removed 'id' variable as it is identical to 'note_str'; I didn't realize previously that I had added this variable myself. Regardless, there is no need for it.

NSynth.py

@@ -85,8 +85,7 @@ class NSynth(datasets.GeneratorBasedBuilder):
         audio_filename = os.path.join(audio_path, filename)
         key = filename.replace('.wav', '')
         yield key, {
-            "id": key,
-            "note": examples[key]["note"],
+            "note": key,
             "note_str": examples[key]["note_str"],
             "instrument": examples[key]["instrument"],
             "instrument_str": examples[key]["instrument_str"],