Make soundfile optional

HuggingFace Spaces doesn't have it installed

fbeeper_hubert.py

@@ -4,11 +4,15 @@
 import argparse
 import re
 import logging
+import warnings
 
-import soundfile
 import transformers
 import torch
 import numpy as np
+try:
+    import soundfile
+except ImportError:
+    warnings.warn("Cannot import soundfile. Reading/writing files will be unavailable")
 
 
 log = logging.getLogger(__name__)